Conceptualization of “Taking the Essence” (bcud len) as Tantric Rituals in the Writings of Sangye Gyatso: A Tradition or Interpretation?

Chülen (bcud len), the practice of “taking the essence”, is an important practice within the Tibetan medical tradition. Through nourishing the body with the so-called depleted “essence”, not only can one extend their lifespan but the practitioner can also restore their physical vitality. In recent years, this practice seems to be shifting away from the traditional religious mode of chülen involving tantric practices and rituals. Among the Tibetan medical literature, chülen is much emphasized in its religious aspects in the two important 17th century Tibetan medical commentaries on the Four Tantras (Rgyud bzhi) by the regent of the Fifth Dalai Lama, Desi Sangye Gyatso (Sde srid sangs rgyas rgya mtsho, 1653–1705): the Blue Beryl (Vaid. ūrya sngon po) and the Extended Commentary on the Instructional Tantra of the Four Tantras (Man ngag lhan thabs). Both texts are considered to be the most significant commentaries to the Four Tantras and have exerted a momentous impact on the interpretation of the Four Tantras even up to recent times. In their chapters on chülen, an assortment of chülen practices can be found. While there are some methods solely involving the extraction of essence in the material sense, there are also some in the spiritual-alchemical sense which are not observed in the Four Tantras. In this paper, I focus on the elaboration of the Four Tantras by Sangye Gyatso via his portrayal of ritualistic chülen in his two commentaries, where the tantric mode of promoting longevity and rekindling vitality is made efficacious by the operative socio-religious factors of his era, and which still exert their effect on our perception of chülen today.


Background
Rejuvenation, the art and science of restoring youthful vitality and promoting longevity, has been sought after over the course of human civilization. Throughout history, the quest for rejuvenation has been pursued in many cultures and in different forms, and continues into the modern era. Such practices are deeply influenced by the cultural and technological conditions of a particular epoch, and most of these techniques have been closely affiliated with the belief system of those social circles. For instance, alchemical beliefs such as the Philosopher's stone played an important role in shaping the concept of rejuvenation and immortality in pre-industrial Europe (Kauffman 1985, p. 71). In modern times, biomedicine and genomics are considered key to rejuvenation and immortality (Karasik and Newman 2015). Cultural status and social positioning play a pivotal role in understanding how methods of rejuvenation are conceptualized, designed, and brought into efficacy in any given population.
Chülen (bcud len) is an important practice according to both Tibetan religious and medical traditions and are deemed to be effective for rejuvenation. Nonetheless, the term chülen itself is polysemous: in Tibetan, the meaning of chü (bcud) varies from taste, essence, juice, nectar, elixir, to nutriment, while len (len) has the meaning of take, collect, extracting, and take hold of. In recent scholarship, chülen is sometimes translated as "essence extraction" or "imbibing the essence juice", and its equivalent in Sanskrit is rasāyana (Cantwell 2017, p. 181). Extraction conducted in the spiritual domain is noteworthy in recent scholarship, as these spiritual or alchemical practices of "extraction" are assimilated into medical practice under the influence of Buddhist tantric ideation. Oliphant (2016, p. 150) suggested that chülen implies extracting essence through alchemical processes, practice ritual and contemplation. Chülen is also involved in the spiritual aspect, as shown in historical studies such as by Gerke (2012a), Samuel (2012), Oliphant (2016), and Cantwell (2017). Even in the contemporary context where biomedicine predominates, such as at the Mentseekhang (Sman rtsis khang), also known as the Tibetan Medical and Astro Institute in Dharamsala, chülen is used in a religious context (Gerke 2017, pp. 214-15); as it restores the essence of one's exhausted body, it is marketed by them as a "rejuvenation tonic" in the form of Precious Pills. Despite these facts, in the Tibetan medical text Four Tantras (Rgyud bzhi), this extraction of essence can occur solely at the material level, without necessarily involving ritual or alchemical processes.
In this paper, I argue that chülen according to the interpretation of the Four Tantras is not spiritually determined. Chülen is re-interpreted, made efficacious, and broadcast via religious discourse in the two 17th century commentaries of the Four Tantras: the Blue Beryl (Vaid .ū rya sngon po) and the Extended Commentary on the Instructional Tantra of the Four Tantras (Man ngag lhan thabs). As both commentaries are considered to be the most "orthodox" interpretation of the Four Tantras, they exert their impact on how we perceive the Tibetan medical tradition even to the present day. This paper examines how the notion of chülen in the medical context has evolved, re-conceptualized, and connected with ritualistic elements in the works of Sangye Gyatso (Sangs rgyas rgya mtsho, 1653-1705, under the theocratic agenda of the Fifth Dalai Lama Ngawang Lozang Gyatso (Ngag dbang blo bzang rgya mtsho, 1617-1682) in the 17th century.

Etymology of Chülen in the Tibetan Medical Context
What exactly is this "essence" to be extracted? According to the Tibetan-Chinese Medical Dictionary (Dbyangs can lha mo 1993, pp. 138-39), chülen is "a method to prolong lifespan and bodily vigor through the use of substances such as flowers and others", 1 while, according to the Tibetan Medical Dictionary (Dbang 'dus 1983, p. 150), chülen "is the name of the method to obtain once again the exhausted essence of the physical body. According to the teachings of auto-commentary of the Eight Branches, chülen is the method to obtain once again the diminished vital essence". 2 In other words, chülen is to take the essence (nutriment) which the body has lost in the process of aging and sickness.
What is considered to be "essence" is highly subject to cultural interpretation and conceptualization. As noted by Gerke (2012b, p. 197), chülen in the Tibetan sense "involves the extraction of essences from substances, such as stones/minerals (rdo'i bcud len), soil (sa'i bcud len), roots (rtsa ba'i bcud len), flower petals (me tog gi bcud len), but also from the breath (rlung gi bcud len) and awareness (rig pa'i bcud len), which require meditative skills". Thus, chülen practice is not only limited to physical substances, but also engages spiritual constituents which are assumed to promote longevity in Tibetan culture, where essence is extracted from the spiritual domain. With all the different methods of obtaining essences, the practice of chülen in the medical tradition seems not to adhere to a single method, and it seems heterogeneous or even ambiguous at first glance. Depending on cultural, technological, and even political conditions, the hermeneutics of this "essence" depends on how the system of medicine and the human body is conceptualized and medicalized; in our case, this is closely tied with Vajrayāna Buddhist culture, in which essence from a spiritual perspective is believed to be a potent nutriment. 1 me tog sogs rdzas la brten nas tshe sring lus stobs skyed byed kyi thabs shes shig/ 2 lus gyi bcud zad pa de nyid slar len pa'i thabs kyi ming ste/ slob dpon dpa'i bos mdzad pa'i yan lag brgyad pa'i rang 'grel las/ de la ci'i phyir bcud kyi len zhes bya ba zhe na/ bcud la sogs pa nyams pa de slar thob par byed pa'i thabs ni bcud kyis len zhes bya'o zhes gsungs pa ltar ro/ As noted by Walter (2003, p. 23), the concept of essence extraction can be traced back to the 6th or 7th century Bhūtad .ā mara tantra, and was later elaborated. The notion of essence extraction takes on different morphology according to different traditions from that point forward. For instance, among Indic systems, the Nāth of the North Indian tantric tradition carried out rasāyana without much dependence on divine influence. Shaivite practice focused more on the cosmological relationship of man to the universe, while Buddhist practice is characterized by invoking spiritual beings and extracting their essence. This paper explore the Buddhist approach to extracting the essence in influencing the medical conception of chülen by comparing the chapters of chülen in the commentaries to the Four Tantras: the Blue Beryl, and the Extended Commentary by Sangye Gyatso. These two important commentaries prompted later scholars, of both the Tibetan medical tradition and western academia, to assume his views and interpretations of Four Tantras. First, let us examine how chülen is depicted in the As . t .āṅ gahr . dayasam . hitā, the precursor to the Four Tantras.

Chülen in the As . t .āṅ gahr . dayasam . hitā-Using Medicinal Substances as Chülen
The Four Tantras forms the scholarly basis of the Tibetan medical tradition. Its origin can be traced back to the 8th century CE (Yang Ga 2010, pp. 21-22). Although the chronological account for the composition of the Four Tantras is uncertain, early scholars such as Csoma De Körös (1835) suggested that the Four Tantras was translated by the scholar Vairocana from the Sanskrit version and transmitted to Yutok the Elder in the 8th or 9th century, 3 and was later revised and propagated by Yutok the Younger (1126-1202) in the late 12th century. Dash (1975, p. 99) suggests that the Four Tantras depended mostly on the importantĀyurvedic medical text As . t .āṅ gahr . dayasam . hitā. Thus, before we look at the chülen chapter of the Four Tantras, it is worth taking a brief look at the As . t .āṅ gahr . dayasam . hitā upon which the Four Tantras has been modeled.
The As . t .āṅ gahr . dayasam . hitā was authored by Vāgbhat . a (7th century), who is believed to be one of the most influential writers ofĀyurvedic medicine. In Sanskrit, as . t .āṅ ga means the "eight branches" of Ayurvedic medicine, namely the Kāya cikitsā (general medicine), Bāla cikitsā (pediatrics), Graha cikitsā (demonic disorders), Urdhvāñga cikitsā (diseases of the head),Śalya cikitsā (external injuries), Dams . t . ra cikitsā (poisoning), Jarā cikitsā (rejuvenation) and Vr . s . ya cikitsā (aphrodisiacs). Rejuvenation (Jarā cikitsā) is found in Chapter 39 of the Uttarasthāna of As . t .āṅ gahr . dayasam . hitā (Vāgbhat . a 1991, pp. 381-412). This chapter on rasāyana therapy (rasāyana vidhi) states that the methods are expounded by the Hindu sage (rishis)Ātreya, who was a renowned scholar ofĀyurveda and six schools of earlȳ Ayurveda were based on his teachings. According to this chapter, the outcomes of the rasāyana therapy are to obtain "long life, (good) memory, (great intelligence, (perfect) health, youthfulness, (bright) complexion and colour, (bold) voice and magnanimity, increase of strength of the body and the sense organs, perfection in speech, sexual power and brilliance." The therapy should be started at a young age (Vāgbhat . a 1991, p. 381).
This chapter draws several parallels with the Four Tantras, and even uses the same phrases, as noted by Gerke (2012a, p. 333). For example, the chapter begins with a method of purifying the alimentary tract, which is believed to be pivotal prior to the rejuvenation practice. "Rasāyana (rejuvenation) or vājīkara (aphrodisiacs) administered to those whose body has not been purified becomes useless, just as colouring a dirty cloths" (Vāgbhat . a 1991, p. 381). The above phrasing reappears in the Four Tantras. The rest of chapter comprises of twenty-two medicinal essence recipes 4 of different lengths, targeted at rejuvenation under different medical conditions. Apart from the use 3 Contrary to the belief of the Tibetan tradition, many contemporary scholars assume that Yutok the Elder probably did not exist. See (Gyatso 2015) p. 428 notes 198). 4 The twenty-two recipes are: Brahma rasāyana, cyavanaprāśa, triphalā yogas, man . d .ū kaparn .ī -śañkhapus . pī yoga, naladādi ghr . ta, pañcāraviñda ghr . ta, catuh . kuvalaya ghr . ta, brāhmayadi ghr . ta, nāgabalā yoga, goks . ura yoga, vārāhīkañda yoga, citraka yoga, bhallātaka yoga, tuvaraka yoga, pippali yoga, sahasra pippali yoga, somarāji yoga, laśuna yoga,śilājatu yoga, vātātapika rasāyana vidhi, harītakī yoga, and nārasimha rasāyana (Vāgbhat . a 1991, pp. 383-411). of medicinal substances, none of the practices in this chapter of the As . t .āṅ gahr . dayasam . hitā embrace spiritual methods. In other words, rasāyana here is oriented towards purely physical substances. Nonetheless, most of these substances reappear in the corresponding chapter of the Four Tantras, signifying that what are considered "essences" inĀyurvedic medicine are also assimilated and valued in Tibetan medicine. In the turn of the 8th century, King Trisong Detsen (Khri srong lde btsan, 742-797) encouraged Tibetan scholars to go to India in pursuit of Buddhist teachings. During their travels, they brought back Vāgbhat . a's As . t .āṅ gahr . dayasam . hitā, which was at that time considered to be one of the great works of medical theory and practice (Kilty 2010, pp. 4-6). Therefore, in this sense, cultural exchange played a role in conceptualizing the notion of "essence" in the practice of chülen in the form of assimilation from Indic culture. The Four Tantras signified an important point in the development of the Tibetan medical tradition in whichĀyurvedic medical concepts are integrated.

Chülen in the Four Tantras-Chülen with Buddhist Spirituality
Although the Four Tantras is based on the As . t .āṅ gahr . dayasam . hitā, it is not a direct word-by-word translation. The Tibetan has revised and modified the Four Tantras to suit their cultural context. While Tibetan medicine is a mixture of Chinese, Greek, Persian, and many other medical systems, one of the most notable characteristics of its transmission is that the Vedic elements were omitted and substituted with Buddhist approaches. The practice of medicine is subsequently tied to and repackaged with Buddhist elements, where spiritual practice possesses the ultimate authority in healing. For instance, according to the Four Tantras, medicinal efficacy comes not only from medicinal substances but also depends on divine influence attributed to the Medicine Buddha (Sangs rgyas sman bla, or in short, Sman bla), who is a manifestation of the Buddha Shakyamuni (Rinpoche 1995, p. 165). Knowledge of healing is considered to be one of the teachings of the Buddha, which serves to relegate the clinical knowledge built up by empirical experience to a lesser status. This can be noted in the introduction to the Four Tantras, which resembles a classical Buddhist discourse, emphasizing that it was a translation from Sanskrit, with homage to the Buddha at the beginning of the chapter. Teachings were conveyed in the form of a dialogue between Rigpé Yeshe and Yilé Kyé, both of whom are said to be emanations of the Medicine Buddha, symbolizing his heart (spiritual aspect) and speech (tantric initiation), respectively (Dunkenberger 2000, p. 18). At the beginning of the Four Tantras (G.yu thog yon tan mgon po 1982a, pp. 1-3), it is highlighted that the knowledge of healing was transmitted by the Buddha himself in the "celestial palace" (gzhal yas khang) of the "Beautiful City of Medicine" (Sman gyi grong khyer lta na sdug), which is adorned with jewels, medicines, and five types of spiritual perfection. Teachings were given to the four groups of celestial beings: "god" (lha), "sages" (drang srong), "outsiders" (phyi pa, non-Buddhists), and "insiders" (nang pa, Buddhists). According to the Four Tantras, the jewels and medicinal substances that can be found in the abode of the Medicine Buddha can cure four hundred and four diseases caused by imbalances in the three "humors" (nyes pa), or a combination of any two or all three humors; a disease of a cold nature will be cured by warmth and vice versa. Moreover, these jewels and medicines can subdue obstacles that hinder good health, and can fulfill the needs and desire of all sentient beings. Despite such religious characteristics, healing involving magical-alchemical means is barely discussed further in the Four Tantras.
Regardless of the above Buddhist elements, the first few paragraphs of the Nourishing the Old Age-Chülen (Rgas pa gso ba bcud len) in Chapter 90 of the Four Tantras, are simply a translation of the As . t .āṅ gahr . dayasam . hitā. However, one could find more differences as one compares these two works, for example more medicinal substances are listed in As . t .āṅ gahr . dayasam . hitā due to geographical availability. Religious rituals can only be found in this chapter of the Four Tantras and not in the As . t .āṅ gahr . dayasam . hitā (Gerke 2012a, p. 333). Despite the differences, several crucial medicinal ingredients are shared among chülen practices in both the As . t .āṅ gahr . dayasam . hitā and the Four Tantras. The foremost essence stated in the Four Tantras is garlic (sgog pa), which is praised as a superior ingredient for chülen in both texts. A recipe specifically developed for preparing garlic is included in the corresponding chapter of both texts. In theĀyurvedic counterpart, it can be found in the laśuna yoga contained in the Uttarasthāna of the As . t .āṅ gahr . dayasam . hitā, where garlic (laśuna) is considered to be the best rejuvenator, but because it is the nectar from the severed neck of Rāhu, "the twice born" (brāhman .ā s) will therefore not take it because it is from a demon (Vāgbhat . a 1991, pp. 399-403). In the chapter, some medicinal recipes are also shared in common, such as the use of bitumen, leadwort, and myrobalan fruits, as noted by Gerke (2012a, pp. 345-47). Then, two recipes distinctive to the Four Tantras involving Buddhist tantric practice of the five essences and four nectars follow. The chülen recipes in this chapter of the Four Tantras do not cover as much detailed medicine-empowering rituals as can be found in later commentaries such as the Blue Beryl and the Extended Commentary (which I discuss below), but instead they offer brief descriptions of mantra recitation and visualization related to two medicinal recipes. These recipes are known as the "Greater Elixir" (bcud len che ba) and the "Lesser Elixir" (bcud len chung ba), which cannot be found in the Uttarasthāna of the As . t .āṅ gahr . dayasam . hitā. For the Greater Elixir: ... add half dré 5 of the Four Nectars and the Five Essences each, cook while adding buffalo milk and butter of thirty sang, 6 with two dré of molasses and put into a skull cup [and utter] Vairocana om . , Vajrasattva hūm . , Ratnasambhava [trām . ], Amitābha hrī, Karmavajraā.
[Then] Perform the Five Buddha Families and their consorts bodhicitta ejection and withdrawal practice. 7 (G.yu thog yon tan mgon po 1982b, p. 550) Without much elaboration in the text, what the "ejection and withdrawal practice" ('pho 'du) actually means is open to interpretation. I suspect this "ejection and withdrawal" practice is related to the practice noted by White (1998, pp. 71-72), a form of hathayogic technique of vajrolī mudrā, where ejaculation, urethral suction, and the raising of semen via the spinal column is performed. This practice can be traced back to the Nāth Siddhas who believed that semen is the carrier of immortality (Djurdjevic 2014). In the Tibetan equivalent, this practice is mentioned in the Instruction of Essence Extraction (Bcud len gyi man ngag) in the Collected Works of Bodong Penchen Choklé Namgyel (Bo dong pan . chen phyogs las rnam rgyal, 1376-1451) (Bo Dong 1970, pp. 507-601). In this text, Bo Dong explained the theoretical (nang) and practical (phyi) aspects of a practice for chülen of Indian tantric origin. The theoretical aspect involves an elucidation of the working of the subtle body. The practical aspect of this practice is described by the physical intercourse of male and female practitioners. During union, semen is ejected and united with the consort's sexual fluid. The resulting mixture is considered immortal nectar. This mixture, or "nectar", is retracted back to the male practitioner by penile urethral suction. While doing so, the practitioner rests in meditation on the five wisdom Buddhas, and light emanates from the heart center of the practitioner. This visualization is analogous to the one that we discuss below in Blue Beryl and the Extended Commentary in this paper. Nonetheless, why this practice is only briefly mentioned in a mere two sentences in the Four Tantras, and which practice it specifies, requires further research. However, we can at least be confident that this is a Buddhist tantric practice of Indic origin that was inserted into the original As . t .āṅ gahr . dayasam . hitā rasāyana method. During the composition of the Four Tantras, the addition of this tantric practice was not only believed to promote the siddha's longevity but also to fortify the medicinal substances with spiritual essence.
In the Lesser Elixir, a list of medicinal substances is mentioned. As with the Greater Elixir, after putting all the recipe ingredients into a skull cup, the following ritual is performed: Visualize oneself as the Buddha Amitāyus in his palace, utter om . sarva tathāgata am . ita shuddhē ayur dharan . i pusht . im . kuru ye swāhā. Collecting longevity vases from the ten directions, filled with countless immortal nectar. (G.yu thog yon tan mgon po 1982b, p. 550) 5 Tibetan unit of volume measurement (bre) is equivalent to about one liter. 6 Tibetan unit of weight (srang) corresponds to the Chinese unit of weight liang. 7 bdud rtsi bzhi dang brag zhun bre phyed phyed// gud gud bsdus pa'i khu ba khyor ba re/ 'o ma mar srang sum cu chu bcad la/ bu ram sbrang bre do sbyar thod bzang blung/ bai ro tsa na om . / badzra satva hūm . / ratna sambha ba/ a mi ta bha hrī/karma badzraā// rigs lnga yab yum byang sems 'phro 'du bya/ In this recipe, the tantric practice of Amitāyus is utilized. Amitāyus rituals are associated with longevity empowerment (tshe dbang) practices. While the Medicine Buddha has become the prominent figure in healing, when it comes to longevity practices (tshe sgrub), Amitāyus has always occupied a significant status in the Tibetan tradition. The origin of the longevity practice of Amitāyus is difficult to trace, but it can be found in the Nyingma literature before the 10th century, where it was held that Padmasambhava gave his teachings in the form of Amitāyus (Walter 1980a, p. 319); while the earliest Amitāyus chülen practice can be dated back to the 13th century treasure revealer tradition (Oliphant 2016, p. 158). Chülen longevity practices are also closely related to the Gelug school (Dge lugs pa) which emerged as the dominant school in Tibet from 17th century, holding political power over central Tibet. For instance, the Second Dalai Lama Gendun Gyatso (Dge 'dun rgya mthso, 1476-1542) composed an Amitāyus longevity sādhana specifically in his liturgy cycle (Halkias 2013, p. 145). The Fifth Dalai Lama also authored the Instruction of the Pure Immortal Water ('Chi med dwangs ma chu 'dren) from his pure-vision treasure (dag snang gter) (Mullin 1986, pp. 149-72). Therefore, these longevity practices played a special role in the Tibetan concept of nectar and chülen, and are associated with the treasure-revealers (gter ston) of the Nyingma school (Samuel 2012, pp. 272-73), which were valued by the Fifth Dalai Lama.
Coming back to the Four Tantras, the above recipes are just two out of a total of nineteen chülen recipes that involve mantra and visualization. The other seventeen recipes do not fall into the spiritual category. Nonetheless, these two rituals in the Four Tantras are not explicated in any detail. It is too early to conclude from which school they originated at this point. In any case, from the structure of the chapter, these two rituals are neither highlighted nor characterized as advanced recipes. Together with the other seventeen medicinal recipes, they share equal weight of attention. This chapter seems to be a collection of effective chülen recipes available at the time of the composition of the Four Tantras. Nevertheless, it is reasonable to argue that at the stage of the writing of the Four Tantras, extracting the spiritual essence in the Buddhist context has gained its importance as a medical concept of rejuvenation among medicinal practitioners in Tibet. The spiritual essence is assumed to restore life. However, one point we have to take into consideration is that the Four Tantras has been redacted and reprinted throughout the period of Tibetan medical development. These rituals may have been added to the original manuscript of the Four Tantras during its various stages of revision. The version of the Four Tantras used by Sangye Gyatso to write his commentaries on the Four Tantras may not be the same version we use today (Czaja 2007, p. 359). Furthermore, the conceptualization of Medicine Buddha as the source of the Four Tantras instead of human authorship by Yutok the Younger could have been a campaign by the Fifth Dalai Lama to give a Buddhist origin to Tibetan medical practice (Van Vleet 2016, pp. 279-82). Although this is less certain, the version of the Four Tantras that is now available to us could have been redacted during the time of the Fifth Dalai Lama.

Theocratic Medicine-The Two Commentaries as Ritualization of Medical Practice
Together with his regent Sangye Gyatso, the Fifth Dalai Lama established the leading school of medicine and astrology known as the Chakpori Rikjé Dropen Ling (Lcag po ri rig byed 'gro phan gling), named after the Iron Mountain (Lcag po ri) near the Potala Palace in Lhasa (Gyatso 2015, p. 115). Under the auspices of this establishment, the Tibetan medical tradition was systematized and institutionalized (Schaeffer 2003, p. 622), and Chakpori represented a leading authority in medical education until the 1950s (Meyer 2003, p. 117). Led by Sangye Gyatso, the school at Chakpori was the central institution with authority in Tibetan medicine. Sangye Gyatso sought to assert control not only in medical knowledge, but in other areas of religious and intellectual life (Schaeffer 2006, p. 187). The Fifth Dalai Lama's campaign for the Chakpori successfully standardized, homogenized, and controlled the practice of medicine. The addition of religious practice into medicinal preparation assures medicine is practiced within the religious context; as these practices are pivotal to the efficacy of medicinal substances, performing the ritual correctly is the key to therapeutics. These rituals fall into the monastic domain. In the two commentaries of Sangye Gyatso, religiosity and rituals formed a substantial portion of his "orthodox" elaboration of the Four Tantras.
Sangye Gyatso composed several significant treatises that have strongly influenced the Tibetan medical tradition even up to the present day. Among them, three treatises have had momentous impact: the Blue Beryl (Vaid .ū rya sngon po), a commentary on the Four Tantras; the Extended Commentary, 8 which highlights mantras and rituals as healing paradigms; and the Mirror of Beryl (Vaid .ū rya me long), a work on the history of Tibetan medicine. These three treatises represent Sangye Gyatso's approach to the learning and practice of medicine. They stress the importance of medical scholarship, the Mahāyāna ideal of being a virtuous medical practitioner, and the magico-religious aspect of healing. Apart from the Mirror of Beryl, the Blue Beryl and the Extended Commentary refashioned the Four Tantras with Sangye Gyatso's tantric interpretation which is otherwise not observed in the main theme of the Four Tantras: as noted by Gyatso (2015, p. 197), "The Four Treatises [Four Tantras] 9 itself does not acknowledge its tantric debts, nor does it use overtly tantric language". Why did Sangye Gyatso write two commentaries to the Four Tantras and what were his hermeneutic approaches to the Four Tantras? Sangye Gyatso was given less than a year to write the Blue Beryl as demanded by Darmo Menrampa (Dar mo sman rams pa 1638-1710), the court physician to the Fifth Dalai Lama (Czaja 2007, p. 357), who favored the Zur tradition of medicine at that time. We can see from the structure of the Blue Beryl that much of it follows the Four Tantras with elaborations of therapeutic methods, of which many are derived from earlier medical sources. Among earlier sources, the chülen chapter of the Blue Beryl is very similar to Chapter 90, Nourishing the Old Aged (Rgas pa gso ba) of the Oral Instruction of the Ancestor (Mes po'i zhal lung) (Blo gros rgyal po 2005, pp. 714-24) by Zurkhar Lodrö Gyelpo (Zur mkhar blo gros rgyal po, 1509-1579) of the Zur tradition. Oral Instruction of the Ancestor is a detailed commentary on the Four Tantras according to the Zur tradition was written in the middle of the 16th century (Martin 2007, p. 307). In this short timeframe, Sangye Gyatso might have been using the Oral Instruction of the Ancestor as his blueprint for his Blue Beryl. However, further comparative work has to be done to confirm this. In any case, the Blue Beryl is an elaborated version of the Four Tantras, enriching healing efficacy in both the medicinal and religious aspects according to the Zur tradition.
The Extended Commentary takes a different viewpoint. Medicinal recipes are often omitted and focus is put on the magico-religious approach towards healing. The Extended Commentary is more of a compendium of mantras and magical formulae as chief therapeutics, regardless of their original source (Czaja 2007, p. 357). As the Blue Beryl is an important commentary to the Four Tantras, why did Sangye Gyatso need to write something to supplement his exposition? The genre of the "extended commentary" (lhan thabs) has played an important role in the development of the Tibetan medical tradition. Extended commentaries contain innovative forms of diagnosis and treatment that reflect the view of medical practices under the social, cultural, and political stimuli of the time they are produced. In other words, they not only provide information on treatment methods vital to that period, but also provide clues of how the contemporary medical "industry" was organized. As noted by Frances Garrett (2010, p. 302), in conjunction with the flourishing of esoteric practices in the 13th century, medical literature written after that time often mentioned the use of esoteric materials. In the Blue Beryl and the Mirror of Beryl, paradoxically, substances related to esoteric practices were rarely mentioned. However, Sangye Gyatso in the Extended Commentary took a different approach to the practice of medicine. Medicinal substances and treatments, which are esoteric in nature, can be found in his work. Furthermore, a study (Chui 2019) of the Extended Commentary reveals that "secret" (gsang) terms are scattered throughout the manuscript. These secret terms seem to render parts of the Extended 8 Full title Extended Commentary on the Instructional Tantra of the Four Tantras. In Tibetan: Man ngag yon tan rgyud kyi lhan thabs zug rngu'i tsha gdung sel ba'i katpū ra dus min 'chi zhags gcod pa'i ral gri (Sangs rgyas rgya mtsho 1991). 9 Gyatso translated the Four Tantras as the Four Treatises.
Commentary incomprehensible to anyone lacking the decrypting key. This encrypting implement retains the confidentiality of the esoteric tradition, but also hinders modern scholastic investigation.
Not only did the Extended Commentary help Sangye Gyatso to demonstrate his talent, but it was also used to epitomize "Tibetan medicine", or Chakpori medicine to be exact. The Extended Commentary is one of the most important works after the Four Tantras and commentaries on it such as the Blue Beryl. According to Janet Gyatso (2015, p. 115), Sangye Gyatso made the Blue Beryl and the Practical Manual (i.e., the Extended Commentary) the core curriculum for medical training at Chakpori. Likewise, Olaf Czaja noted that "they are the most important textual sources for the training of Tibetan doctors, past and present, and the medical ideas and concepts contained in them constituted the core Tibetan medical thinking" (Czaja 2011, p. 283). The Extended Commentary has endured to become an important text which is still appreciated in the present day.
Therefore, in terms of novel treatment methods, the Extended Commentary reflects the "best therapeutics" and "tantric" conceptualization of illness and healing held by Sangye Gyatso during his time. These treatment methods have much influenced the conceptualization of Tibetan medicine nowadays. For instance, in the Extended Commentary, a hard-to-treat illness was classified as magical-religious in nature, and elements such as demons were considered contributory causes of disease (Czaja 2011, pp. 269-70). In handling "illness caused by demons" (gdon nad), the Extended Commentary employed a collection of ritualistic medicines which were seldom found in the root text of the Four Tantras (Gyatso 2015, p. 393). A point to note here is that a majority of diseases and disorders could be administered by using mantras and other magical formulae, which exemplified the tantric healing characteristic of the Tibetan medical tradition much appreciated during that period (Czaja 2007, p. 357). As suggested by Czaja (2007, p. 357), Sangye Gyatso may have tried to limit the ritualistic therapeutics in his Blue Beryl, so as to keep it faithful to its root text, the Four Tantras. Rather, he put these novel methods into the Extended Commentary.
Through these two commentaries, Sangye Gyatso shaped and imposed medical professionalism upon Tibetan medical practitioners, and prescribed moral, behavioral, and religious values which every talented practitioner should uphold in accordance with his Chakpori standards. Moreover, the conceptualization of disease and its treatment methods are much theorized via the Buddhist worldview, to the extent that rituals favored by the Chakpori tradition are incorporated as medical practice.

The Blue Beryl-Chülen Accentuated by Rituals
The chülen chapter of the Blue Beryl basically follows the organization of the Four Tantras, beginning with medicinal-only recipes similar to those of the Four Tantras. When it comes to the first ritual in the Greater Elixir, the original ritual in the Four Tantras is preceded by an elaboration Sangye Gyatso referred to as the practice of the deity Vajra Armor (Rdo rje khrab ring) of the Nectar Vase (Bdud rtsis bum pa). 10 This text mentioned by Sangye Gyatso is closely related to the Nyingma terma entitled Nectar Vase of Immortality ('Chi med bdud rtsi bum pa), as acknowledged by Czaja (2007, pp. 363-64), which is an important source of the Blue Beryl and the revision of the Four Tantras. Simioli (2016, p. 409) noted that the long life practice of the Nectar Vase of Immortality shares similarities also with Chapter 91 of the Instructional Tantra (Man ngag rgyud) of the Four Tantras, which discusses virility (ro rtsa). A point worth noting in the ritual is that Sangye Gyatso integrates the Nectar Vase by Padmasambhava, which was one of the more influential Nyingma tantric works current during his time of composition. The second ritual in the Lesser Elixir is the elaborated long-life ritual of Amitāyus. Sangye Gyatso further explained the chülen chapter of the Blue Beryl by emphasizing rituals to extract spiritual essence into medicinal substances, while some of the medicine-only recipes of the Four Tantras are omitted.
This arrangement of the Blue Beryl promotes the importance of Buddhism in conceptualizations of healing, as noted by  and Gyatso (2004), where healing is highlighted in its spiritual aspects. The chülen chapter of the Blue Beryl first discusses various medicinal recipes such as the benefits of garlic and bitumen. It metaphorically states that garlic is the blood of demigods (lha min khrag). When it comes to the so-called Greater Elixir, a ritual of greater detail is described compared to the one in the Four Tantras. While some authors such as Gerke (2012a, p. 351) suggest that this is an elaboration of the ritual in Four Tantras, there is also the possibility that another ritual is added to the original ritual mentioned previously in the Four Tantras. Although the translation may have appeared in Parfionovitch (1992, p. 119) work on the medical paintings made by Sangye Gyatso to complement his Blue Beryl, what follows is my translation for the ritual that shows that the painting is quite faithful to the text of the Blue Beryl: ... put all the ingredients into a skull cup of good quality and place it on a table. First perform the ritual of refuge as mentioned in the Nectar Vase (Bdud rtsi bum pa). Generate your own personal yidam, while realizing emptiness, to the center of the skull cup utter om . and mūm . . Visualize a white Buddha Vairocana and his consort holding a dharma wheel in the right hand and a skull cup in the left hand. To the east utter hūm . and lām . . Visualize a blue Vajrasattva and his consort holding a vajra and a skull cup. To the south utter trām . and mām . . Visualize a yellow Ratnasambhava and his consort holding jewels and a skull cup. To the west utter hrīh . and bām . . Visualize a Buddha Amitābha and his consort holding a lotus and a skull cup. To the north utterāh . and tām . . Visualize a Buddha Amoghasiddhi and his consort holding a vajra-cross and a skull cup. The skull cups they are holding are full of nectar. From their head, throat, and heart emanate respectively the letters om . ,āh, and hūm . . From the letter hūm . on their heart emit light rays of five colors, inviting the Five Buddhas inseparably. Visualize the Five Buddhas in the state of meditative union. From the place of union descends the essence of red and white bodhicitta, dissolving into the medicinal substances, turning them into longevity nectar. Inconceivable light radiates from one's own heart and reaches to: the ten directions with many offering goddesses, the Buddhas and their spiritual sons, the Medicine Buddha abiding in the Pleasant Sight mountain, Copper-colored Mountain and Maratika Cave where long-life Padmasambhava and the goddess abide, peaceful and wrathful dakinis are all delighted, and with all their powers and all the blessings of longevity they dissolve into the medicine in the skull cup. Then visualize light rays emitting from oneself and illuminating all beings of the six realms, purifying their defilements, leading them to the realization of the Medicine Buddha and his consort. This blessing of longevity transforms into essence of all kinds and the illumination of the five elements: the earth element turns into yellow, the fire element turns into red, the water element turns into blue, the wood element turns into green, and the metal element turns into white. 11 These five illuminations converge and dissolve into the nectar in the skull cup. (Sangs rgyas rgya mtsho 2005, pp. 1477-78) For the Lesser Elixir, after preparing all the medicinal substances in a skull cup, the following ritual should be performed: First perform the ritual of refuge as in the Nectar Vase mentioned previously. Visualize the letter bhrūm . in front of you transforming the skull cup into a squared celestial palace with four doors decorated with jewels. Within the palace there is a lotus on a sun and moon disk emanating white light from the letterāh . . With all the offerings to the Buddhas absorbed into the letterāh . , the letter then transforms completely into Amitāyus with a white body, in meditation posture holding a nectar vase in his hands. Inside the vase there is a crossed vajra. At the center of the crossed vajra, there is a nectar-filled moon-jeweled box protected by Hayagrīva with a red body holding a staff in his right hand, and his left hand is in the mudra of threat. From one's heart are emitted light rays from the mantra to the heart of Amitāyus, invoking his awareness. Then from Amitāyus's heart light radiates to the ten directions, illuminating all the offerings, deities, and beings, delighting them. With that, all the essence of the realms are collected and dissolved into the jeweled box inside the vase. Utter the mantra om . sarva tathāagata am . ita shuddheāyur dharan . i pusht . im . kuru ye swāhā, collecting longevity essence from the ten directions, filling the vase with immeasurable immortal nectar.
Both rituals, the practice of five Dharani Buddhas and Amitāyus, are found in the chapter Nourishing the Old Aged in the Oral Instruction of the Ancestor (Mes po'i zhal lung) (Blo gros rgyal po 2005, pp. 718-20) mentioned above. Therefore, they are not Sangye Gyatso's personal additions. These practices appear to originate with the Zur tradition, but can be traced further back to the Nyingma tradition. The ritual here is analogous to the Vimalamitra's Eight Chapters on Nectar (Bdud rtsi bam po brgyad) on the blessing or accomplishing of medicine. This discourse was passed on to Tibet during the 8th to 9th century and formed a part of the Nyingma Collection of Tantra (Rnying ma rgyud 'bum), influencing the accomplishing of medicine in Tibetan medical development (Garrett 2010, pp. 303-4). The Nyingma tradition teaches that the consecration of medicine is sealed with the fluid resulting from sexual intercourse on the skull of a Brahmin in the center of a practice mandala. All these rituals are not done in a symbolic sense but rather in a literal sense as noted by Davidson (2002, p. 197): in Indian esoteric Buddhism, the sexual fluid realized in union is ingested as nectar. In this chapter of the Eight Chapters on Nectar, as translated by Walter (1980b, pp. 168-77), during the ritual a skull cup from Brahmin is to be place in the middle of the mandala. This skull cup should be of auspicious and pure lineage, and should be round like a yoni. Then, the medicine is placed inside the skull cup. Sexual union are performed by the yogin and the consort during menstruation, and the resulting semen and menses become superior quality rasāyana. Walter (1980b, p. 145) opined that the rasāyana of Vimalamitra was initially intended for yogic practice to bring siddhi or magical power. This ritual is quite different from the ejection and withdrawal practice mention above in the Four Tantras. The ejection and withdrawal practice mentioned above involved retrieving nectar by the suction of the male organ, while here in the Blue Beryl it involves a mixing of medicine of the visualized nectar into the skull cup. This shift in tantric approach corresponds to Samuel (2012, pp. 277-78) finding that tantric practices were developed and reconfigured to "include major features of the full Tantric ritual and context (man . d . alas, deity visualization, mantras, dhāran .ī s) but which do not include the new, fully-developed internal yogic practices, or the specifically sexual yogic exercise that accompany them". Nonetheless, as the medical paintings showed, all of the literal and sexual practices were replaced by visualization practices in the Blue Beryl. These paintings assured religion's role in the healing arts in Sangye Gyatso's Chakpori medicine. Spiritual essence extracted in the visualization-only manner became an important part of chülen practice. The reason for this is obvious, as sexual intercourse and the consummation of their physical products are not compatible with medicine idealized by Chakpori monastic morality.

The Extended Commentary-Chülen is Further Tantricized
As we read from his chapter on chülen in the Blue Beryl, treatment methods are a compendium of medicinal and rituals, with medicine-only recipes being prominent. Nonetheless, we find only two rituals involving therapeutic methods in the Extended Commentary, and Sangye Gyatso almost completely omitted all the other medicinal recipes, only retaining the Greater Elixir recipes. Following the Greater Elixir as described in the Four Tantras, he inserted a medicinal recipe and another recipe involving ritual. Here is my translation of the chülen chapter of the Extended Commentary (Sangs rgyas rgya mtsho 1991, pp. 649-67): The method of rejuvenation and nourishing the old are divided into benefits and recipes. Benefits: Increasing longevity without sickness, physical strength, clarity of the senses, mental sharpness, and libido.
Recipes: Detoxify the body according to the presenting body ailment before performing chülen. If the body is not detoxified accordingly before practicing the nourishment, the outcome will not be effective, like dyeing a dirty cloth.
After detoxification, take the Four Nectars and Five Essences formula. The Five Essences are: bitumen (brag zhun), the essence of earth which nourishes muscles; calcite (cong zhi), the essence of rock which nourishes bones; molasses (bu ram), the essence of wood which nourishes strength; honey (sbrang rtsi), the essence of flowers which nourishes skin tone; and white butter (mar dkar), the essence of grass which is a nutritious nourishment. The Four Nectars are juniper berry (shug 'bras), fragrant rhododendron (ba lu), ephedra (mtshe), and frankincense (mkhan pa). These four are also known as evergreen nectars which can increase longevity. The above nine medicines can supplement nourishment, cure the nine fatal diseases, ward off old age, enabling the patient to regain the body of a sixteen-year-old with the power of a lion, the strength of an elephant, the radiance of a peacock, the speed of a horse, and the longevity of the sun and moon.
This introduction to chülen is very similar to the Four Tantras and the Blue Beryl. Then, Sangye Gyatso continues with the first recipe: The recipe for preparing the Four Nectars Five Essences Medicinal Butter is as follows: Ground a dré of good quality neutral calcite into the size of chang fruit, cook with five dré of water, reducing the volume to one dré, and remove the impurities. Obtain a half dré of pure iron-containing bitumen by soaking in water and filter out the impurities. Together with the Four Nectars, a half dré for each, boil and reduce separately to the amount of a handful each. Mix the above ingredients into three dré of freshly obtained red-cow milk, boil and reduce as mentioned above, stir in four sang of fresh butter, wait unit it separates into two layers, put on a low fire, let it steep without boiling. Until it coagulates to a thickness such that it can still be stirred with a finger, let it cool. Then mix in a sang of molasses and a sang of white honey.
To the above six ingredients add: strength empowering salep orchid (dbang lag), eye-clearing carex (rtswa a wa), heat-generating medicinal ginger (sga smug), aphrodisiac snow frog meat (gangs sbal sha) ground into powder, and this constitutes the medicinal butter preparation. This is the method of the Jang (Byang ba) tradition.
The recipe is almost the same as the one mentioned in the Blue Beryl. The above recipe emphasizes that it was taken from the Jang school, which Sangye Gyatso did not mention in the Blue Beryl. As noted by Czaja (2007, p. 352), it is possible that the court physicians of the Fifth Dalai Lama tended to lean towards the Zur school, and the Blue Beryl could have been co-authored by other physicians at the court of the Fifth Dalai Lama who minimized mention of the Jang tradition. Otherwise, in the Extended Commentary, he fully expressed his succession to both the Zur and Jang traditions (Van Vleet 2012, p. 61). Nonetheless, further research has to be done on this. Then, the recipe continues with a consecrating ritual similar to the one in the Blue Beryl: Then put the preparation into a nice skull cup at the center of the altar. First perform the ritual of refuge and vow, then visualize oneself as the deity Dorje Trapring "Vajra Armor" (Rdo rje khrab ring) as mentioned in the Nectar Vase (Bdud rtsi bum pa). Realizing emptiness, visualize in the center of the skull cup the letter om . manifesting into a white-faced Buddha Vairocana and his consort with the letter mūm . . Together they hold a dharma wheel in their right hand and a skull cup full of nectar in the left hand. In the east are the letters hūm . and lām . , manifesting the blue-faced Vajrasattva and his consort, holding a vajra in the right hand and skull cup full of nectar in the left. In the south are the letters trām . and mām . , manifesting yellow-faced Ratnasambhava, holding jewels in his right hand and skull cup full of nectar in his left hand. In the west are the letters hrīh . and pām . , manifesting in Buddha Amitābha and his consort, holding a lotus in the right hand and a skull cup full of nectar in the left. In the north are the lettersāh . and tām . , manifesting in Buddha Amoghasiddhi and his consort, holding vajra-cross in the right hand and a skull cup full of nectar in the left. The above five Buddhas and consorts are in union. Visualize from their place of union descending red and white bodhicitta and dissolve this into the medicinal substances, turning them into longevity nectar. Light radiates from one's own heart (light rays of the five Buddhas) and reaches the mandala arising opposite the practitioner.
The rest of the description is similar to that of the Blue Beryl. In fact, this Greater Elixir is almost the same as the one in the Blue Beryl with some differences in detail in the practice. In the Blue Beryl, the deity is not specified, as the instruction only mentioned to generate the deity according to the practitioner's own tradition. Nonetheless, here in the Extended Commentary, Sangye Gyatso recommends the reader to generate himself into the deity Dorje Trapring, the "Vajra Armor," which is a practice in the Nectar Vase. The chapter continues with another medicinal recipe: Another recipe uses the secret medicine "Ever-weeping Bodhisattva" (rtag tu ngu), 12 and while the flowers are available in many different colors, the yellow one is the best in quality. It looks like saxifraga, covered with greasy silvery powder on the stems and leaves, the root looks like that of the silverweed. Collect when the flowers and leaves are robust, and dry them in a cool place. Take two dré of this with one-hundred myrobalan (a ru), twenty-five beleric myrobalan (ba ru), two handfuls of emblica (skyu ru), three handfuls of salep orchid, half a handful of long pepper (pi pi ling), bitumen, calcite and the Five Nectars medicine. Roughly grind the above to the size of pebbles, and boil in eleven dré of non-salty river water. Filter the above and add four dré of dzö 13 milk and two sang of dzö butter, boil and reduce to a thickness that can hold a spoon upright. Remove from heat and let it cool. Then add three pieces each of myrobalan, pomegranate (se 'bru), cardamon (sug smel), cinnamon (shing tsha), long pepper, "Ever weeping Bodhisattva", saffron, clear salt, and ten notches of fine coarse sugar (rgyal mo ka ra). Grind and stir in extra salep orchid and the secret medicine to increase bodily strength, and carex for clear eyesight. Take the above medicine at dawn if one has a good digestive heat, otherwise take it at the morning or in the evening. Keep everyday activities light, and the diet according to general nourishment. Avoid consuming meat if high in bile and phlegm.
From the above translated text, one finds that the medicinal substances are quite common and can easily be found in the Tibetan materia medica. Moreover, the secret medicine "Ever-weeping Bodhisattva" (Saxufraga egregia) is revealed in this chapter. Elsewhere in the Extended Commentary to conceal important or sensitive information from outsiders, the secret medicine is not disclosed to the reader and special encryption is used to conceal the information. These "secret medicines" (gsang sman) were intentionally hidden by authors, and keys for their decryption exist (Chui 2019). 14 The secret 12 A medicinal herb also known as rtag ngu 'od ldan. According to Arya (1998, p. 84), rtag ngu 'od ldan (Saxifraga egregia) "cures bad blood, generates good blood, improves eyesight, maintains physical balance, increases lifespan and acts as an elixir". 13 Dzö (mdzo) is a cross-breed of male yak and female cow. 14 I found the keys to these "secret medicines" dispersed in two separate texts. Each one provides a partial solution to the encryption and both must be consulted in order to fully utilize the medicinal recipes in the text. One, attributed to Ngawang Sangye Palzang (Ngag dbang sangs rgyas dpal bzang), a student of Sangye Gyatso, is the Single Lineage of Secret Medicine: The term in this chapter makes it possible for the reader to fully prepare the medicine in accordance with the recipe when compared with recipes found in other chapters. Whether the information has been disclosed by a later author revising the Extended Commentary or Sangye Gyatso intentionally put it there requires further research. However, in our context, this "Ever-weeping Bodhisattva" is given extra attention and designated as a "secret medicine," thus indicating its potency. Now, we come to the second recipe. For the Lesser Elixir, the ritual is completely replaced by another one. In the first section of this new Lesser Elixir recipe, Sangye Gyatso metaphorically mentioned the five nectars which are quite different from the other "five nectars" mentioned elsewhere in tantric literature. 15 Furthermore, he clearly showed the use of the substances is symbolic in nature rather than literal: Another method is using equal amounts of the following five nectars in the preparation.
The nectar of gods (lha), "Ever Weeping Bodhisattva", with a hundred benefits, can cure blood-bile disease due to heat.
The nectar of nagas (klu), salep orchid, with a hundred benefits, can regenerate bodily vigor and sexual fluid. The hands 16 with five fingers are the best in quality and are not divided into male or female. However, if prescribed for a male patient, a female hand (i.e., with 3 fingers and slender in shape) should be used, while for a female patient a male hand (i.e., with 4 fingers and thicker in shape) should be used. Hands with joints are known as demon hands, and should not be used for medicinal purposes.
The nectar of sages (drang srong) is gold myrobalan, with a hundred benefits; it can balance and unify the body.
The nectar of dakinis (mkha' 'gro) is calcite, with a hundred benefits; it can overcome phlegm diseases.
The nectar of humans (mi) is molasses which is heavy and thick, with a hundred benefits, is best for overcoming wind disease. Varying amounts may be used to address specific disease conditions.
From the above, one might notice that these nectars are herbs rather than particularly special ingredients. Elsewhere in the Extended Commentary, Sangye Gyatso suggested substitution when some substances are not available. This recipe is also subjected to a blessing ritual: Grind the above ingredients into powder and roll into the size of a piece of stag scat, while reciting om .ā h . hūm . for blessing. On the first of every month, generate oneself as the Wrathful Guru (Drag po rtsal). Visualize the letter hūm . at the heart center manifest as the white dakini holding a hooked-knife in the right hand and a skull cup full of nectar in the left. The hūm . at the heart emanates light rays endowed with the essence of nirvān . a and sam . sāra, dissolving into the nectar in the skull cup. The nectar in the skull cup spills out, and through the three channels of the heart center it spreads throughout the whole body. Take the above prepared medicine during visualization. The addition of minor ingredients can produce a fine body and skin quality, sharpen the mind, tame gods and demons, and give better eyesight at night. These are just a few of the benefits.
Here, the new Lesser Elixir of Amitāyus in the Blue Beryl is replaced by a meditation practice of the Wrathful Guru. An important point to note here is that this recipe brings to mind a 14th century text written by Rigdzin Gödem (Rig 'dzin rgod ldem 1337-1408) of the Jangter (Byang gter) tradition (Rig 'dzin rgod ldem 1980). This text was translated by Cantwell (2017, pp. 186-88), in which I found the medicinal recipes and rituals are almost identical in the Extended Commentary but without the section in which the quantity of the substances to be used is given. Since this chülen text was composed around the 14th century and the Extended Commentary in the 17th century, it is possible that Sangye Gyatso incorporated this Nyingma ritual into his writing. The integration of this ritual is recognizable since the Fifth Dalai Lama inclined towards the Jangter tradition while also holding the Nyingma tradition. This is probably because the lineage transmission of the Jangter went from Rigdzin Gödem to Rikdzin Lekden Dorjé (Rig 'dzin legs ldan rdo rje, 1512-1628), Wangpo Sé (Dbang po sed, 1550-1607), Rikdzin Ngakgi Dangpo (Rig 'dzin ngag gi dang po, 1580-1639), and then to the Fifth Dalai Lama (Karmay 2002, pp. 32-33). The deity Wrathful Guru also appeared in the secret visions of the Fifth Dalai Lama a few times (Karmay 1998, pp. 18-19, 21, 24, 27). The integration of the practice of the Wrathful Guru showed Sangye Gyatso's preference for which practice was to be used for extracting the essence; in this case, a ritual closely linked to the Fifth Dalai Lama.
The Fifth Dalai Lama's preference for the Nyingma school was so great that he has been described as a "crypto-Nyingmapa" (Snellgrove 1968, p. 196). The Fifth Dalai Lama was tied closely to the Nyingma and Kagyu lineages (Karmay 2014, p. 43), and later in his early monastic training he was deeply devoted to the Nyingma master Zur Choying Rangdrol (Karmay 1998, p. 3). As he continued his studies, he took a special interest in Nyingma tantric doctrines "from the viewpoint of political power" (Stein 1972, pp. 171-72). In fact, the Fifth Dalai Lama states in his autobiography that rather than choosing the Panchen Lama or any other Geluk masters, he took the great Nyingma lama Zur Choying Rangdrol (Kun mkhyen zur chos dbyings rang grol, 1604-1657) as his "root guru", and his "root master," and the Fifth Dalai Lama considered these Nyingma rites as "indispensable to reign over the country" (Karmay 2014, pp. 215, 355, 8). 17 Moreover, as noted by Van Vleet (2012, p. 62), Chakpori medicine depends heavily on the Nyingma tradition. Thus, it is not surprising to see chülen in the Chakpori context, following the interpretation of Sangye Gyatso, is linked with Nyingma rituals; the significance of spiritual essence is much emphasized, and the nature of chülen shifts from a basis in medicinal substances to one rooted in spirituality.
Another point worth noting when comparing these three Tibetan medical texts is that the prizing of garlic as a superlative medicine in both the Four Tantras and the Blue Beryl has been omitted in the Extended Commentary. Even in other chülen recipes in the Extended Commentary, we cannot find a single use of garlic or its relatives onions, shallots, leeks, and chives. Since garlic is rich in "essence", why is it not mentioned in the text? If my assumption that the Extended Commentary was written for audiences observing tantric practices, or perhaps from the tantric practitioner's perspective, this is because garlic is considered a "black" food, which hinders tantric practice. As mentioned above, garlic is considered to be the blood of demons and is avoided by Brahmins. Garlic should be avoided for many other reasons related to tantric practice, since garlic is believed to unbalance bodily subtle energies and drive deities away (Barstow 2017, p. 10). Garlic is regarded as six kinds of pungent food, with onion, spring onion, shallot, chives and leeks, which can cause mouth and skin odor, difficulties in concentrating during practice, increased sexual desire and increased liver fire (Lee 2017, p. 228). From these three medicinal recipes, we can see that the use of garlic is not mentioned. This withdrawal of garlic from the chapter exemplifies the power of religion in determining the choice of medicinal herb to be used.

Sangye Gyatso's Orthodox Interpretation of Chülen Still Holds Today
By the end of the 16th century, the Gelugpa had become the dominant sect in Tibetan Buddhism. With the Fifth Dalai Lama as the leader of the Buddhist Ganden Podrang Government in the 17th century, the Gelugpa consolidated its political control over central Tibet. 18 "Buddhist doctrine" (chos) and "political power" (srid), referred to as the "assembly of doctrine and politics" (chos srid gnyis 'brel) were combined, comprising a "dual governance" (lugs gnyis) of theocratic sovereignty (Halkias 2006, p. 103). Through their immense literary, political and institutional force, the Gelugpa hegemony influenced and utterly controlled not only the cultural life of the Tibetan Plateau (Schaeffer 2013, p. 348), but also its medical knowledge. Tantric practices appear to be further elaborated and even highlighted in the Blue Beryl and the Extended Commentary, the two most important commentaries to the Four Tantras authored by Sangye Gyatso, the skillful regent of the Fifth Dalai Lama. This period witnessed a remarkable enrichment of the Tibetan medical genre. In these two commentaries, medicine practiced without ritual is considered to be inadequate and without full efficacy. Through these two commentaries, Sangye Gyatso wished to propagate the authority in medical practice of the Chakpori school (Van Vleet 2012, p. 61).
The Fifth Dalai Lama, exerting his supreme influence on the practice of medicine, promoted chülen from a medicinal concept to a religious one. While these two important commentaries of the Four Tantras by Sangye Gyatso occupy a prominent position in the Chakpori school, at the same time, they set forth his subjective interpretation for later successors and commentators in the medical tradition as benchmarks for their works even up to the present day. For more than two hundred years, the Blue Beryl and the Extended Commentary were not only the most important texts in Tibetan medical education but also served as orthodox interpretations at the Mentseekhang and at other Tibetan medical colleges. Referencing Sangye Gyatso's hermeneutics, both Tibetan medical practitioners and modern academics conceptualize their approaches with his elucidations of theoretical medicine in mind. However, Sangye Gyatso's campaign has not only been limited to professional circles, but has also found resonance with a wider public. The best example, as mentioned above, are Sangye Gyatso's medical paintings for the Blue Beryl, which heavily embeds Tibetan medicine within mystical practice. These painting have been used as pedagogical tools from the time of Sangye Gyatso until today. With their publication by Parfionovitch (1992) in Tibetan Medical Paintings, the spiritual intent of chülen is reinforced. The two rituals are graphically presented and made famous in particular by two of the seventy-nine medical paintings (Parfionovitch 1992, pp. 119-22) made during the time of Sangye Gyatso (Czaja 2007, p. 352). These two paintings popularize and promote chülen as a spiritual practice, just as he did with the paintings for other medical interventions given in Four Tantras, as noted by Gyatso (2014).

Concluding Remarks
Are we shifting away from an entire tradition, or merely re-evaluating an interpretation in the era of biomodernity? It has been observed that over many generations even before the present day, the practice of Tibetan medicine had been progressively secularized (Gyatso 2015). Specifically, it has even been suggested that chülen may have been re-invented at the Mentseekhang in the context of the Sorig OTC "rejuvenation tonic" (Gerke 2012b). This suggests that the spiritual aspect of Tibetan medicine has been much neglected and that it is no longer practiced as it was "traditionally". Nonetheless, as we see from the many kinds of chülen practices in the Four Tantras and its predecessors, chülen practice is medicinal in nature. The ritualistic chülen outlined in this study is an interpretation of Sangye Gyatso rather than an uninterrupted medical tradition. The notion of "essence" that we perceive today has been re-conceptualized by the Blue Beryl and the Extended Commentary. Chülen as a spiritual practice is probably a product of the medical theocracy of the Fifth Dalai Lama. A deeper understanding of this notion will make us reconsider whether chülen-or even Tibetan medicine itself-has changed to suit biomodernity, losing its spiritual identity along the way.
Funding: This research received no external funding.

Conflicts of Interest:
The author declares no conflict of interest.