Zhuangzi’s Copernican Revolution from the Perspective of Structural Realism

Abstract

This article discusses Zhuangzi’s metaphysical theory from the standpoint of a form of structural ontology that was developed by neurophilosopher Northoff and which differs from typical studies of Zhuangzi’s metaphysics. According to Nossoff’s world–brain relationship, a structural positivism based on relationships, the body is nested in the world and the brain is nested in the body. Northoff contends that elements of Eastern philosophy support this viewpoint. I have examined three aspects of Zhuangzi’s philosophy by interpreting his texts: the existence of a world independent from the subject and mind, the subject and mind dependent on the world, and the coexistence of differentiation and inclusiveness between the world and the subject. The problem this article attempts to address is how Zhuangzi achieved a Copernican revolution within the framework of non-reductive neurophilosophy, bringing about a shift away from non-anthropocentrism.

1. Introduction

My writing strategy is as follows. In the first section, I introduced the relevant concepts of reductive and non-reductive neurophilosophy and argued why Northoff’s theory is a moderate structural realism. I also presented his judgment on Zhuangzi’s Copernican revolution. In the second section, I first clarified the three criteria of the Copernican revolution, then analyzed Zhuangzi’s philosophy according to these criteria. In the third section, I summarized the content and elaborated on the significance of Zhuangzi’s Copernican revolution.

1.1. World–Brain Relationship

With the rapid development of functional brain imaging techniques, such as magnetic resonance imaging (MRI), philosophical questions concerning consciousness, mind, and other general human interest have also entered the field of vision of neuroscientists. The interaction between philosophy and neuroscience appears to have become natural and logical. The idea of incorporating philosophical questions into the realm of natural science is not uncommon in the history of philosophy. However, it was Churchland who first introduced the term “neurophilosophy.” In her book Neurophilosophy, published in 1986, Churchland explicitly defined and introduced this term (Churchland 1986). Churchland has since discussed this idea extensively in her later work. She advocated abandoning the traditional paradigm of philosophical research and embracing the latest advances in psychology, neuroscience, and other related fields for philosophical inquiry. This research paradigm experienced significant growth and development over the next two decades (Churchland 1987).

However, in subsequent developments, neurophilosophy began to be considered as in decline (Bickle 2019). The reason behind this decline lies in the majority of neurophilosophers adopting a stance known as “ruthless reductionism”, which advocates for fully incorporating philosophical propositions within the scope of neuroscience (Bickle 2003). They argue that consciousness can be entirely reduced to neural activities in the brain. Consequently, certain philosophical concepts that cannot be explained by neurophilosophy are dissolved or eliminated. At the same time, neuroscientific philosophy has increasingly adopted a highly technological trend. Researchers in this field must possess considerable knowledge of biological sciences and neuroscience. As a result, it is challenging for researchers with only a single background to share their research findings. In other words, the research direction has shifted from broad conceptual inquiries to specific issues within the field of neuroscience. This shift has been driving the development of neuroscientific philosophy rather than neurophilosophy itself.

Based on reflecting on Churchland’s ideas, neurophilosopher Northoff proposed the notion of non-reductive neurophilosophy. He argued that the paradigm of fully incorporating philosophical concepts into neuroscience is a form of reductionist neurophilosophy. He also believed that this approach attempted to replace philosophy with neuroscience. In contrast, non-reductive neurophilosophy posits that neuroscience and philosophy are not mutually exclusive but can engage in an equal and mutually beneficial dialogue. According to this perspective, both fields can draw upon each other’s advancements to jointly explore the mechanisms underlying consciousness and other related issues (Northoff 2016). More precisely, the reductionist neurophilosophy promoted by academics like Churchland aims to reduce the ontological, epistemological, and ethical notions of philosophy to experiential truths inside the brain’s neurological activity. This strategy would lead to the erasure of specific, unique philosophical ideas. On the other hand, non-reductive neurophilosophy claims that “by providing methodological tools to investigate interdependencies and mutual constraints systematically, opposes the reduction of concepts to facts” (Chen and Northoff 2021). This methodology fundamentally uses concept–fact interactivity as a non-reductive methodological tactic, successfully preventing the dissolution of distinctive philosophical ideas. Through discoveries in neuroscience, Northoff established “temporo-spatial dynamics” as the basis for neuro-mental transformation and proposed a fresh ontological framework of the link between the world and the brain. The “Spatiotemporal Theory of Consciousness (TTC),” which views spacetime as the intermediary for developing the brain and consciousness, is the name he gave to this theory. It encompasses four mechanisms: spacetime nestedness, spacetime alignment, spacetime expansion, and spacetime globalization (Northoff and Zilio 2022). This is the main characteristic of Northoff’s most recent ontology concept. “The spatiotemporal structure enables the world, the brain, and consciousness to form an interconnected whole, in which the elements acquire definite positions and the attributes previously considered intrinsic in this connection” (Yang and Qi 2022). Why, then, is this arrangement being proposed? Acknowledging that even the most advanced brain imaging techniques cannot provide definitive answers to how consciousness is generated is crucial. While we can scan and identify the active states of different brain regions during a particular conscious experience, we cannot directly scan the conscious experience within the brain. This raises the question of how subjective personal consciousness is connected to the brain. From a third-person perspective as an object of observation, the brain seems unable to address the problem of consciousness from the first-person perspective, which philosophers call the “hard problem.” This highlights the challenge of bridging the gap between the subjective experience of consciousness and its underlying neural processes (Chalmers 1997). It can also be understood as a subjectivity dilemma.

By studying people suffering from disorders such as depression, schizophrenia, and bipolar disorder, Northoff found that the balance between the resting state level of the brain and external stimuli was disrupted in these patients. Based on this observation, he deduced that the acquisition of healthy consciousness relies on the balance between the resting state of the brain and external stimuli (Northoff 2018b). In other words, attaining healthy consciousness depends on a certain equilibrium between the brain and the outer world. Consciousness is not purely generated by internal brain activity or solely influenced by external stimuli. Consequently, Northoff proposed a model of the world–brain relationship, suggesting that the brain and the outer world (the surrounding environment) are intimately interconnected. This world–brain relationship would replace the mind–brain problem in philosophical inquiry.

1.2. Why the “World–Brain Relation” Is a Moderate Structural Realism

The emergence of structural realism was a response to the anti-realism trend that arose following Thomas Kuhn’s theory of scientific revolutions and paradigm shifts. According to Larry Laudan’s Pessimistic Meta-Induction (Laudan 1981), a considerable number of previously successful conclusions in the history of science have been overturned. Following the principles of induction, what justification do we have to believe in the truthfulness of the currently successful scientific theories acknowledged by scientific realism? Laudan provides numerous historical facts from the development of science to support his viewpoint, which has become one of the most potent arguments employed by anti-realists against scientific realism. We cannot ignore the temporal constraints on scientific advancement; in fact, scientific ideas frequently display the trait of continuous updating. Are there any aspects that hold and remain stable amongst this continual development? Structural realism appeared during the ongoing argument between realists and anti-realists. It was initially put forth by John Worrall and developed by James Ladyman. It has since been generally separated into ontic structural realism (also known as structural realism about the universal) and epistemic structural realism (also known as structural realism about internal relations). Regarding the unobservable world, epistemological structural realism posits that entities exist beyond our cognitive reach. In contrast, ontological structural realism argues that entities do not exist and only structures and relations do (Wei 2015).

Northoff’s proposal of the world–brain relationship considers relational structure as an ontological existence while also acknowledging the existence of relational objects but denying their substantial status. Essentially, this represents a moderate form of ontological structural realism. Traditional ontology often regards entities with specific physical or mental attributes as the primary focus, emphasizing attributes over relationships. In contrast, the world–brain relationship views relational structures as entities with inherent existence. While the objects in these relationships possess their corresponding attributes, the relationships take precedence over the attributes of the objects. Consequently, the emphasis on the mind, often highlighted in traditional philosophy, no longer takes precedence over the world in the context of the world–brain relationship. Meanwhile, the philosophical debate on the mind–brain relationship, which was previously contentious, loses its significance because neither of them possesses substantial existence. “In describing the world-brain relationship, I presuppose a relational-based ontology known as structural realism. It posits that the relationship between the world and the brain is an integration or connection of a part (such as the brain) with the whole (such as the world). This integration or connection constitutes the necessary ontological conditions for potential mental features (such as consciousness)” (Chen and Northoff 2021).

As a form of structural ontological perspective, the world–brain relationship posits that it is the fundamental source for the generation of human consciousness. However, the hard problem persists as a challenge. Northoff suggests the existence of a common currency that serves as the foundation for transforming neural processes in the brain into human consciousness.

Northoff uses the example of water as an analogy to illustrate his point. Just as the common currency of H₂O allows for the transformation of water between solid, liquid, and gaseous states, he argues that a common currency exists in the form of temporo-spatial dynamics between the brain and consciousness. The temporal continuity and spatial extension of brain activity constitute a precise internal concept of time within the brain. Furthermore, as the brain is part of the world, its spatiotemporal concept is embedded within the spatiotemporal concept of the world. This allows the brain to synchronize its spatiotemporal concept with that of the external world, enabling us to generate accurate consciousness and avoid neural disorders. Furthermore, in neuroscience, there is evidence of scale-free activity in the brain that serves as an empirical test of this embedding phenomenon (Northoff 2018a). Indeed, the focus of the text lies in Northoff’s theoretical constructs, which position ontology within a continuum rather than a specific substance with attributes. The pursuit of consciousness is no longer confined to a singular physical or mental entity; instead, it emerges from the interaction between the nervous system and the external environment. It encompasses the harmonious relationship between the subject and the world.

Northoff’s holistic thinking may not be easily understood or accepted within the Western cultural framework that has long since been dominated by dualistic tendencies. However, when we shift our perspective to examine Chinese philosophy, and even East Asian culture, we can sense a resonance with cross-cultural vibrations, just as Northoff’s interpretation of the dialogue between the shadow and the faint light at the edge of the shadow in Zhuangzi’s chapter on Qiwulun 齊物論. The shadow was questioned by the soft light at the edge of the shadow (Wang Liang 罔兩) about why its actions were not determined by itself and what controlled the activities of the shadow. This brief dialogue connects the subject, the shadow, and the faint light. The pale light cannot exist apart from the shadow, the shadow cannot exist apart from the subject, and the subject’s behavior seems to be manipulated by something. In this context, we would not consider the duality between the shadow and the faint light, because although they have different properties, they can exist precisely because of their existence within the relationship with the subject and the shadow. In other words, the relationship is the condition for their existence. “The faint light has no way to define itself and its characteristics independently outside the shadow—the inherent nature of the faint light is relational” (Northoff 2016).

In summary, we have analyzed the proposal of the world–brain relationship and why it is considered a form of moderate structural realism. The world–brain relationship is a new response to the problem of consciousness proposed by Northoff, based on clinical observations of unhealthy brains and reflections on traditional reductionist neuroscientific philosophy. This is a form of non-reductive neurophilosophy, where relationships within this paradigm replace the ontological mental or physical attributes. In this framework, the body is situated within the spatiotemporal relationship with the brain, and the brain is located within the spatiotemporal relationship with the world. The relationship between the individual and the world is emphasized, and Zhuangzi’s contemplation on the issue of human consciousness and his profound argument on the subject-world relationship aligns with Northoff’s line of thinking. As Northoff has mentioned, Zhuangzi indeed accomplished a “Copernican revolution”.

2. Zhuangzi’s “Copernican Revolution”

2.1. Criteria for Judging a Copernican Revolution

We must clarify the judgment criteria to elucidate further why Zhuangzi accomplished this revolution. “The Copernican revolution” appeared in Immanuel Kant’s Critique of Pure Reason in 1787. In the preface to the second edition of his seminal work, Critique of Pure Reason, the philosopher Kant wrote: “The situation here is the same as the original idea of Copernicus, who, assuming that the explanation of the motion of the heavenly bodies could no longer proceed smoothly when all the stars revolved around the observer, tried to let the observer revolve by itself and instead let the stars stay at rest to see if this might achieve better results. In metaphysics, we can experiment similarly regarding the intuition of objects” (Kant 2004, p. 15). Just as Copernicus replaced the geocentric model with the heliocentric model, Kant, like Copernicus, subverted the relationship between subject and object. He believed that the human being actively engages in understanding the objective world. Reason enables humans to acquire knowledge of objective things, thereby establishing the subjective position of human beings. At the same time, human reason is not unlimited. There exist things in themselves that transcend reason and are beyond human comprehension. While acknowledging the subject’s capacities, Kant also limits the subject’s cognitive abilities. He denies that the subject can know all objects of the world solely through reason, which can be seen as a form of overcoming anthropocentrism to a certain extent. It is inherent to human nature to adopt a vantage point when understanding things and to believe in what they observe, such as the early geocentric model. Both Kant and Copernicus shifted the point of observation in the human perception of the world. They transferred the advantage of intuition by considering ourselves as the observers, resulting in different perspectives on the world. Following this line of thought, Northoff has defined the “Copernican revolution” from the standpoint of structural ontology as “the quest for a methodological (or epistemological) strategy that allows us to view the subject and the world simultaneously in a non-anthropocentric manner” (Northoff 2020).

Furthermore, by examining the ideas of Kant, Alfred N. Whitehead, and Martin Heidegger, Northoff argues that the true Copernican revolution involves viewing the world as independent of the body and mind. The human body and mind should be seen as dependent on this world for their existence. Additionally, humans are situated within the natural world and do not possess divinity. Northoff simplifies this into three criteria for judgment: (a) The (natural) world is defined as independent of the subject and mind. (b) The subject and its mind are defined as dependent on the world. (c) World–subject inclusion and world–subject differentiation co-exist (Northoff 2020). Northoff, in his article, compares Kant, Whitehead, and Heidegger with Zhuangzi and argues that these three philosophers, Kant, Whitehead, and Heidegger, did not truly accomplish the Copernican revolution in the complete sense. But he only uses the example of Zhuangzi playing drums and singing after his wife’s death to make his argument and does not delve deeper into the internal aspects of Zhuangzi’s philosophy. In this article, we will follow the triple criteria of the Copernican revolution under the framework of structural ontology and approach the profound implications of Zhuangzi’s philosophy from within the cultural context of Chinese philosophy. In the upcoming sections, specifically Section 2.1, Section 2.2 and Section 2.3, we will begin analyzing Zhuangzi’s philosophical ideas by employing a textual interpretation approach based on understanding their underlying principles. The primary objective of this analysis is to provide an objective portrayal of the true essence of Zhuangzi’s thoughts. Subsequently, we will examine why Zhuangzi successfully fulfilled the three criteria above within the framework of structural realism.

2.2. Definition of the (Natural) World as Independent of the Subject and Mind

The most prominent aspect here is Zhuangzi’s attitude toward life. We can glimpse Zhuangzi’s perspective on the relationship between the individual and the world from the rich writings he left behind. In the Dazongshi 大宗師 chapter, Zhuangzi states, “Life and death are an inevitable process of life, much like the constant rotation of day and night, conforming to the laws of nature. They are beyond human intervention, aligning with the principles of the ever-changing world. 死生，命也，其有夜旦之常，天也。人之有所不得與，皆物之情也” (Chen 2016) Life and death are predetermined; they are natural phenomena, much like the alternating cycles of day and night. They are beyond human control. Although it may seem that birth, aging, illness, and death pertain to the individual, Zhuangzi asserts that they are not determined by the individual alone. Birth, aging, illness, and death are inevitable processes that every person must experience. In the Dazongshi 大宗師 chapter, Zhuangzi uses the examples of Zi Si (子祀), Zi Yu (子輿), Zi Li (子犁), and Zi Lai (子來) to illustrate his unique perspective on sickness and death. Zi Yu (子輿) fell ill and transformed into a person with “a hunched back, with the cavities of his five viscera facing upward, his chin hidden beneath his navel, his shoulders higher than the top of his head, and his cervical spine protruding towards the sky 曲僂發背，上有五管，頤隱于齊，肩高於頂，句贅指天” (Chen 2020). Zhuangzi employs an extremely exaggerated portrayal that most people find difficult to accept. Furthermore, through the words of Zi Yu (子輿), Zhuangzi suggests that this condition is bestowed by the Creator. Indeed, this illustrates Zhuangzi’s belief that everything follows its inherent principles, and that the processes of birth, aging, illness, and death in human life are determined by external forces. Specifically, Zhuangzi refers to the interplay of yin and yang, representing the dynamic and complementary forces in the external world as the governing principles. Zi Si (子祀) said to Zi Yu (子輿), “Do you dislike your current appearance? 女惡之乎?” (Chen 2020). Zi Yu (子輿) replied, “Why would I dislike myself this way? If nature were to transform my left arm into a rooster, I would use it to crow. If nature were to change my right arm into a slingshot, I would use it to shoot birds and roast them for food. If nature were to turn my buttocks into wheels and my spirit into a horse, I would seize the opportunity and ride this chariot, no longer needing to search for a carriage or horse. 亡，予何惡！浸假而化予之左臂以為雞，予因以求時夜；浸假而化予之右臂以為彈，予因以求鴞炙。浸假而化予之尻以為輪，以神為馬，予因以乘之，豈更駕哉！” (Chen 2020). This optimistic acceptance of suffering is precisely what Zhuangzi wants to express. “The attainment of life is due to harmony with the right timing, while life is lost due to following the laws of nature. Accepting and adapting to fortunate circumstances can prevent sorrow and joy from infiltrating the heart. The ancients called this liberation from the painful predicament of being inverted. However, the reason for not being able to achieve self-liberation lies in being bound by external things. Moreover, it has been a long time that things cannot change beyond the limits of nature. So how could I possibly detest my current transformations? 且夫得者，時也，失者，順也；安時而處順，哀樂不能入也。此古之所謂懸解也，而不能自解者，物有結之。且夫物不勝天久矣，吾又何惡焉？” (Chen 2020). According to Zhuangzi, people acquire or possess something only as a temporary state, which happens to be at a suitable time, but not eternally. When that moment passes, people should calmly accept the loss of something. Zhuangzi emphasizes the importance of being in tune with nature’s giving and taking back, not feeling excessive joy over external objects or extreme sorrow over personal setbacks. By doing so, one can achieve complete liberation. However, if one cannot earn total freedom, they will be trapped by material things and bound by external influences. Zhuangzi clarified the existence of a world that is not subjectively determined by humans and emphasized that we should conform to the rational arrangement of the world.

Zhuangzi suggests that life and death are not based on opposition. On the contrary, everything is endowed by Qi (氣). In the chapter titled Zhibeiyou 知北遊, Zhuangzi expresses his views through the example of Zhi (知)1 asking the Huangdi (黃帝) for advice on the concept of “Dao (道)”. He declares that life and death have the same nature and that valuing life does not imply a fear of death. Death marks the beginning of life. The cycle of life and death is essentially the flow, development, and dissipation of Qi (氣). Understand this point, and there is no need to worry about death. This applies to all things in the world. Therefore, we can perceive life as marvelous and death as foul and decaying. The fantastic can transform into the foul, and the foul can also transform into the extraordinary because they are all part of the same Qi (氣). By accepting the changes in Qi (氣) with equanimity, we can also proceed through the natural process of aging, illness, and death without worry, anxiety, or deliberate avoidance (Chen 2020). This is not an isolated case. In the Dazongshi 大宗師 chapter, Zhuangzi, speaking through the mouth of Confucius, praises Meng Suncai, saying, “Those who have passed away only disturb their physical bodies but do not harm their spirits. It is only the location of the spirit that changes, not its true death. Only Meng Suncai understands this, so when people cry for him, he cries along with them. That’s why he does it. 且彼有駭形而無損心，有旦宅而無情死。孟孫氏特覺，人哭亦哭，是自其所以乃” (Chen 2020). When Meng Suncai’s mother passed away, he cried like anyone else, mourning the death of a loved one. However, although he shed tears, he did not grieve. Yan Hui believed that Meng Suncai did not truly embody benevolence and righteousness. In Yan Hui’s view, the death of a loved one should be deeply mourned. But Zhuangzi believed that Meng Suncai, by realizing that death is merely the extinction of the physical form without affecting the spirit, understood that there was no real cause for sorrow. Even though the physical body no longer exists, the soul does not disappear. In reality, there is nothing to be saddened about. Crying is merely performed to conform to societal norms and customs.

Indeed, Zhuangzi tries to blur the line between life and death, as in the case of Zhuangzi’s dream of a butterfly. Was the butterfly in Zhuangzi’s dream, or did he exist in the butterfly’s dream? This is Zhuangzi’s reflection on the reality of the world. Life and death are simply transformations from one state to another. While alive, one should go with the flow, aligning with the natural order and safeguarding one’s own life by avoiding actions that jeopardize it. When faced with death, there should be no aversion, sadness, or worry. Humans are powerless against nature, and death is the beginning of life. The gains and losses of a person are all arranged by nature. It is only necessary to follow the course of nature, act following destiny, and do nothing against it. Instead, we should contemplate more on Zhuangzi’s attitude towards the individual and the world they inhabit.

To some extent, Zhuangzi diminishes the importance of the individual and emphasizes the decisive role of heaven (the world). However, we should envision the era in which Zhuangzi lived: a time of social upheaval and frequent warfare, where human life was not guaranteed. This made Zhuangzi more capable of understanding the impermanence of life. Yet, Zhuangzi did not become disheartened; he did not abandon respect for the individual due to the harsh external environment of the world. While acknowledging the existence of a world beyond human control, Zhuangzi also emphasizes the capacity of individuals to preserve their own lives, facing the ups and downs of life with a more open-minded attitude.

Northoff believes that Zhuangzi considers birth and death as complementary aspects of an intrinsic transformation within the world rather than as mutually contradictory. In the world depicted by Zhuangzi, transformation is an inherent feature that exists before human cognition and does not depend on the human subject. More specifically, birth and death are not exclusive features of human beings; the transformation between life and death is an inherent aspect of the world’s existence and reality. Humans merely share specific world characteristics, and birth and death are part of this shared experience (Northoff 2020). More specifically, birth and death are not exclusive features of human beings; the transformation between life and death is an inherent aspect of the world’s existence and reality. Humans merely share specific world characteristics, and birth and death are part of this shared experience. The processes of birth, aging, sickness, and death are rules all human beings in this world share. Even though humans are conscious of these transformative processes, they exist independently of human cognition. This perspective aligns with external realism, suggesting that reality exists independently of various representations humans may have about it.

2.3. Definition of the Subject and Its Mind Dependence on the World

First of all, when we are born into the world, we have some connection with it. After we are born, we inevitably form social relationships that are in a constant state of growth and development. Zhuangzi shows caution about such social relations and has his thoughts on this issue. In the Renjianshi 人間世 chapter, Zhuangzi, through the voice of Confucius, states: “There are two fundamental principles in the world that cannot be violated. One is a heavenly mandate, and the other is a moral duty. Children naturally show respect and love for their parents; this is an innate instinct that cannot be explained from within. Subjects serve and obey their rulers, a moral duty imposed by humans. No matter where one goes within heaven and earth, there will always be rulers in power, which is an inescapable reality. These are the principles that cannot be violated. 天下有大戒二：其一命也，其一義也。子之愛親，命也，不可解於心;臣之事君，義也，無適而非君也。無所逃於天地之間，是之謂大戒” (Chen 2020). Zhuangzi acknowledges two types of social relationships humans cannot escape: filial love between parents and children and the duty of subjects to serve their rulers. One pertains to family relationships, while the other involves societal and political connections. These are relationships that even the most free-spirited individuals cannot deny or ignore. They are necessary relationships that significantly influence a person’s life. In other words, once a subject is born into the world, they are bound to be connected to the world they inhabit. The state of their life and their mental state cannot exist separately from the world. This is a positive affirmation that Zhuangzi places the individual in a position of dependence on the planet.

Based on recognizing such two meaningful relationships, it seems that Zhuangzi should not be passive and avoid the world, so why does he present a transcendent side? In his book Philosophy of Zhuangzi 莊子哲學, Wong Bo states, “In my view, this choice is mainly based on two factors: one is the genuine experience of the world as Zhuangzi perceives it, and the other is the reflection on the Confucian and worldly relationships. The former is the most crucial, while the latter is indispensable. These two factors often intertwine in specific discussions, making it difficult to distinguish between them clearly” (Wang 2004). Specifically, Zhuangzi lived during a turbulent era known as the Warring States period, characterized by constant warfare and power struggles among feudal lords. It’s worth noting that Zhuangzi was not a noble or a fallen noble but a commoner. In such times of war, the livelihood of the common people was severely affected, and their safety and security were not guaranteed. It is understandable that Zhuangzi, exposed to the harsh realities of the laboring masses, would feel disappointed with the ruling class. Therefore, he chose to retreat from political affairs and escape the chaotic world. However, there is a question that arises here. In the previous discussion, it was mentioned that Zhuangzi acknowledges the active nature of the ruler–subject relationship. So why does he appear to evade political matters in his behavior and other thoughts on political relationships? In the Zhuangzi, rulers are often depicted as ignorant, cruel, and unresponsive to advice. For example, “I have heard of the ruler of the state of Wei卫. He is young and acts with arbitrary authority. He handles political affairs recklessly, unable to see his faults. He heedlessly burdens the people, causing countless deaths throughout the country. It’s like little grass filling up a big lake, and the people have nowhere to turn. 回聞衛君，其年壯，其行獨。輕用其國而不見其過。輕用民死，死者以國量，乎澤若蕉，民其無如矣！” (Chen 2020). In this passage, Zhuangzi uses the anecdote of Yan Hui seeking advice from his teacher to depict a ruler who is young, impulsive, negligent in political matters, and imposes harsh punishments. Under the rule of such a leader, death is pervasive, and the people have no place to seek refuge. Through these descriptions, we can discern that, in Zhuangzi’s portrayal, any possibility of transforming this ruler into a benevolent leader is eliminated. Firstly, the ruler’s young and vigorous nature implies a long reign, which means the people will have to live under oppressive rule for a considerable period. It can also be understood as Zhuangzi’s dissatisfaction with a ruler who fails to govern wisely and effectively despite being in the prime of life. Secondly, this ruler’s autocratic and unreflective behavior completely shuts down the avenue for scholars to offer advice and counsel to the ruler. Under such hopeless circumstances, even entering into government service would not change the reality. It is precisely based on a deep understanding of the inherent nature of rulers that Zhuangzi abandons the path of serving in government to save the country.

The second aspect is the example provided by Confucian scholars to Zhuangzi. As mentioned earlier, Zhuangzi has a profound understanding of the current state of rulers and the people, demonstrating his highly insightful nature. Confucianism advocates for active engagement in the world, yet the rulers were engrossed in conquest and power struggles during that time, showing little concern for the well-being of the people, let alone embracing the benevolent governance advocated for by Confucianism. Even Confucius himself, despite his travels among different states, found it difficult to realize his political ideals. The same can be said for Mencius. Witnessing the outcomes of Confucian scholars entering into government service, Zhuangzi naturally became even more disillusioned with the idea of actively saving the world. Similarly, in the Renjianshi 人間世 chapter, Zhuangzi used the examples of Yan Hui 顏回, Yegongzigao 葉公子高, and Yan He 顏闔 to illustrate the difficulty of changing the entire world.

Upon witnessing the lack of benevolence in the ruler, Yan Hui expressed his desire to Confucius to enter government service and save the country. However, Confucius replied that even, if Yan Hui went to that country, he would die because rulers are difficult to change. Confucius explained that Yan Hui’s virtuous conduct would instead highlight the ruler’s lack of benevolence, regardless of whether it was intentional or not. The ultimate consequence would be being killed. “Forcing oneself to speak of benevolence, righteousness, and norms in front of a tyrant is like using someone else’s wicked actions to showcase one’s virtue. Such an approach can be considered harmful. Those who harm others are bound to be harmed by others, and by adopting such a course, you may face harm from others! 而強以仁義繩墨之言術暴人之前者，是以人惡有其美也，命之曰災人。災人者，人必反災之。若殆為人災夫” (Chen 2020). Yan Hui further inquired, “What if I maintain a dignified appearance, possess a humble heart, and consistently strive diligently? Would that be effective? 端而虛，勉而一，則可乎” (Chen 2020). Confucius also rejected this idea, saying, “The ruler of Wei is fierce and violent, displaying his arrogance openly. Moreover, he is unpredictable in his emotions. People dare not contradict him in the slightest, and he uses this to suppress their true feelings and different opinions, indulging his desires. Daily attempts to influence him through morality will be ineffective, let alone trying to advise him with great virtues. 夫以陽為充孔揚，采色不定，常人之所不違，因案人之所感，以求容與其心，名之曰日漸之德不成，而況大德乎?” (Chen 2020). How can a capricious ruler who only seeks subservience from his subjects is receptive to sincere advice? Yan Hui further suggested, What if he employed the words of ancient sages to advise the ruler? Confucius also responded with a negative answer to this gentle approach, saying, “Although this method may be persistent, it carries no blame. However, it is just that, and how can it truly influence him? 雖固亦無罪，雖然，止是耳矣，夫胡可以及化!” (Chen 2020). If using great virtues cannot influence the ruler, how can these gentle methods be effective? While it may help preserve one’s life, it serves little purpose, and therefore there is no need to serve such a ruler. The next person to appear is Yegongzigao, who held the role of an envoy. He was perplexed because if he wholeheartedly carried out the assigned diplomatic mission from the ruler, he would live in constant fear and strain himself mentally and physically. On the other hand, if he failed to complete the task entrusted to him by the ruler, he would face the ruler’s reprimand. Confucius advised him with an ancient saying, “Convey plain words, not excessive words, and then you can more or less ensure your own safety. 傳其常情，無傳其溢言，則幾乎全” (Chen 2020). The meaning is to faithfully convey the ruler’s intentions, disregarding one’s worries about the success or failure of the task so that, regardless of whether the mission is accomplished or not, one can ensure their safety. This approach is about participating in political affairs without imposing one’s own will and mindset, passively accepting them, and not exerting excessive force. Zhuangzi believed that, if one is too eager to achieve something and forces others to do things, it is like actively provoking a fierce beast and will result in backlash. The last person to appear is Yan He, who is about to become the teacher of the crown prince. The crown prince is extremely cruel, “His character is marked by brutality and a thirst for killing. If one accompanies him day and night without conforming to the laws and norms, it will inevitably harm the country. Conversely, if one conforms to the laws and norms, it will harm oneself. His intelligence is sufficient to recognize others’ faults, but he does not understand why others make mistakes. 其德天殺。與之為無方則危吾國，與之為有方則危吾身。其知適足以知人之過，而不知其所以過” (Chen 2020). This means the crown prince can only see others’ faults and does not understand them. If Yan He remains inactive and allows things to develop unchecked, it will harm the country. However, if he takes action, he will be met with the crown prince’s dissatisfaction and resentment. In such a situation, Zhuangzi, speaking through Qu Boyu 蘧伯玉, expresses, “If he behaves like an innocent child, you should also act like an ignorant and inexperienced child. If he does not draw a line between you, then you should also not draw a line. If he acts without restraint, then you should also act without restraint. 彼且為嬰兒，亦與之為嬰兒；彼且為無町畦，亦與之為無町畦；彼且為無崖，亦與之為無崖” (Chen 2020). Faced with such a crown prince, one must be cautious and vigilant. First, if the crown prince behaves like a baby, Yan He should also act like a baby. If the crown prince exhibits freedom and lack of boundaries, Yan He should also display freedom and lack of limits. If the crown prince is unrestrained, Yan He should also be unrestrained. In summary, one must initially go along with the crown prince and gradually guide him toward change.

The story of Yan Hui can be seen as Zhuangzi’s appeal to those who aspire to enter government service. On the other hand, the stories of Yegongzigao and Yan He are directed toward those who are already involved in state affairs as courtiers. Zhuangzi negates the effectiveness of entering government service and strongly advises against forceful intervention. He believes that after entering government service, one should avoid excessive exertion, as being too persistent will only lead to a senseless loss of life, bringing no benefit to the country or its people. In the stories presented by Zhuangzi, the rulers are portrayed as negative figures. The sovereigns are depicted as cruel and physically strong, while the crown prince, who represents the nation’s hope, lacks benevolent qualities. They are incapable of bringing about positive changes in people’s lives. Under the governance of such rulers and the future inheritors of power, the entire nation can be seen as hopeless.

On the contrary, those who eagerly seek to enter the service of rulers possess a benevolent heart. This reflects Zhuangzi’s thoughts and aspirations. Amid such turbulent times, it is unlikely that Zhuangzi did not have the desire to govern the world. However, the harsh realities and hopelessness of the era extinguished his aspirations to enter the ranks of government. Those who yearn to save the world are either killed or have their fighting spirit destroyed, becoming obedient pawns under the rule of sovereigns. It can also be understood that these individuals are attempting to achieve their governance ideals in a roundabout way. However, for a chaotic political landscape, such an indirect approach is like adding a drop of water to a burning cartload of firewood; it cannot achieve the goal of saving the world. Therefore, Zhuangzi chose to give up rather than stubbornly pursue a futile path, unlike the Confucian approach of knowing the impossibility yet persisting. He understood the consequences of following the impossible and deemed it unnecessary.

Indeed, both the era in which Zhuangzi lived and the influence of Confucianism on Zhuangzi’s thinking indirectly reflect how the historical context shapes individual thoughts. Zhuangzi advocated for the transcendence of worldly concerns, but why did such thoughts of transcendence arise? Can we say that Zhuangzi’s ideas were purely imagined without any basis? From acknowledging the inescapable nature of the two relationships to Zhuangzi’s negation of the act of entering officialdom, it is evident that the subject depicted in Zhuangzi’s writings relies on the world for its existence. The external world profoundly influences the subject’s choice of behavior. Without the external conditions of the world, the subject and the mind cannot be sustained.

According to Searle’s viewpoint, “All representations of reality are made relative to some more or less arbitrarily selected set of concepts” (Searle 1995). The various concepts generated by Zhuangzi are based on his understanding of certain aspects of the world; we cannot assert that Zhuangzi comprehended the entirety of the world’s facets. The topics of Zhuangzi’s debates are based on the world outside the individual, whether he admits two forms of social interactions or condemns rulers and discourages active engagement in social and political activities. From a narrative standpoint, Zhuangzi prefers to explain his important concepts through specific instances from real life and speculative scenarios instead of creating his ideas purely within subjective imagination, cut off from the outside world. This further indicates Zhuangzi’s goal of emphasizing that people and their brains depend on the world’s external reality rather than being isolated from it. Indeed, there is a more direct example in Zhuangzi’s story of “Pao Ding Jie Niu” (The Butcher Ding Cuts Up an Ox). In the narrative context of Zhuangzi, the butcher initially sees just an ox; then, it becomes a pile of meat and bones. This story illustrates how Zhuangzi portrays the transformation of perception in the butcher’s mind as he performs his task, emphasizing the interconnection between the individual and the external world. Firstly, Butcher Ding delves into the internal body of the ox existing in the world, comprehending the various intricate relationships among its bones.

Consequently, he acquires exceptional anatomical skills. The success of Butcher Ding is inseparable from his profound grasp of external relational aspects. If Butcher Ding had solely focused on observing the ox from his perspective and had not taken it as the point of observation, understanding its internal structures, he would have found it challenging to achieve success. Furthermore, at a more abstract level, a low-level butcher can only see the ox as a whole. We cannot say that he does not know the ox, but he lacks knowledge of the ox’s bone structure.

In contrast, a skilled butcher not only perceives the ox as a whole entity but also comprehends the relationships among its bones. Therefore, understanding or not understanding something depends on different aspects of the object. Not knowing the bone structure of the ox does not imply a lack of knowledge of the ox as a whole. The lack of familiarity with one aspect of something does not prevent understanding another. Moreover, an advanced butcher can perceive aspects of the ox beyond its entirety, indicating that humans can transcend specific cognitive perspectives and engage in the transformation of their cognitive viewpoints. According to the outlook of transcendental perspectivism proposed by Bo Mou, the consciousness depicted by Zhuangzi possesses transcendent characteristics. In other words, within Zhuangzi’s descriptive framework, humans can understand a certain object from a specific perspective while transcending particular human viewpoints (even transcending the collective human perspective) to comprehend the object from other perspectives. (Mou 2008) This coincides with Northoff’s view, as he argues that Zhuangzi precisely achieved the transcendence of the human subjective point of observation, leading to his accomplishment of this Copernican revolution. When facing his wife’s death, Zhuangzi transcended the individual’s point of word, enabling him to overcome the grief resulting from his wife’s passing. “By shifting from an observation point inherent within the subject to a transcendent observation point, he saw something beyond his wife’s life and death: death is no longer the endpoint of his wife, and birth is no longer her beginning. Death and birth are both integral parts of the world as a whole, and the life and death of his wife are intertwined with the continuous transformations occurring within the world” (Northoff 2020). This is precisely because the human subject and mind depend on various world realities, sharing certain characteristics with the world, and the possibility of transcending the individual’s observation point exists.

2.4. Coexistence of World–Subject Inclusion and World–Subject Differentiation

The Dao serves as the foundation in Zhuangzi’s philosophy. The cycles of life and death, as well as the gathering and dispersing of Qi, follow the principles of the Dao. At the same time, the Dao is also a manifestation of the external world. As individuals who are part of the Dao, humans are considered to be integral parts of the world rather than separate entities that are elevated above the rest of nature. Even in the Confucian tradition, human beings are considered part of the natural world and subject to the same principles governing the universe. From a metaphysical perspective, humans, like all other things, derive their existence from the ultimate principle of Taiji (太極, the Great Ultimate) and the interaction of Yin (陰) and Yang (陽). This view is reflected in the teachings of neo-Confucianism, such as Zhang Zai’s concept of “All people are my fellow beings; all things are my peers. 民胞物与”2 and Zhu Xi’s idea of “Li Yi Fen Shu 理一分殊”.3 In this tradition, humans are not considered to possess divinity or a special status separate from the rest of the world. This perspective represents a consistent tradition in Chinese philosophy.

In the Qiwulun 齊物論 chapter of the Zhuangzi, Zhuangzi says, “Mao Qiang (毛嬙) and Li Ji (麗姬) are renowned as beautiful women among people, but when fish see them, they dive deep into the water; when birds see them, they soar high into the sky; and when deer see them, they swiftly run away. So, among humans, fish, birds, and deer, who truly understands the true beauty of the world? 毛嬙麗姬，人之所美也，魚見之深入，鳥見之高飛，麇鹿見之決驟” (Chen 2020). Humans consider Mao Qiang and Li Ji beautiful, but they are not seen as beautiful in the eyes of other creatures. So, what is beauty? Zhuangzi uses this example to question whether humans possess genuine aesthetic ability. In Zhuangzi’s philosophical standpoint, humans do not hold a central position in the world. Therefore, Zhuangzi shifts the perspective from humans to external things.

From their vantage point, humans tend to believe that what they see is true and trustworthy while being reluctant to believe in things that surpass their cognitive boundaries. This is similar to Plato’s “Allegory of the Cave”. Zhuangzi’s shift in observational perspective allows him to see another side of the world, challenging the anthropocentric view. At the same time, humans do not possess any transcendent status. This aligns with the concept of “world–subject inclusion” advocated for by Northoff. But Zhuangzi’s philosophical thinking does not stop there. While humans are embedded within the world and do not transcend the realm of nature, there are still inherent differences between humans and non-human entities. Zhuangzi deeply recognizes this distinction. Zhuangzi advocates that human beings can transcend the confusion of form and external objects, and that they should gradually forget those things outside of the spirit to achieve true freedom, realizing the fact that human beings are part of the natural world but also arguing that human spirits can be cultivated to achieve spiritual freedom, which is the aspect of human beings that is different from other things in nature. In this way, the combination of the observation point beyond the subject and the observation point within the subject enables Zhuangzi to look down on the natural course of birth, old age, sickness, and death, but also to attach great importance to the individual experience of life, presenting a non-anthropocentrism unique to Zhuangzi.

In the chapter of Dazongshi 大宗師, Nanbozikui (南伯子葵) asks Nüyu (女偊) about how to attain the Dao. Nüyu’s response is as follows: “I have a reserved method to impart the Great Dao to him. After three days, he will be able to forget about the world. Once he has forgotten about the world, I will again have a reserved method to impart the Great Dao to him, and after seven days, he will be able to forget about everything. Once he has forgotten about everything, I will again have a reserved method to impart the Great Dao to him, and after nine days, he will be able to forget about himself. 吾猶守而告之，參日而後能外天下；已外天下矣，吾又守之，七日而後能外物；已外物矣，吾又守之，九日而後能外生” (Chen 2020). In other words, one can achieve the state of forgetting the world, forgetting external objects, and forgetting the existence of one’s own life. It is a progressive process. To forget the world, we first need to let go of the entire world. Then, we have to forget about external things and the possessions we own. Finally, we must forget about our existence. According to Zhuangzi, our lives are endowed by the Dao and also taken back by the Dao. This Dao cannot be attained solely through learning. In the Tao Te Ching, Laozi states that “the more knowledge one seeks, the more desires and embellishments increase day by day; the more one seeks the Tao, the more desires and embellishments decrease daily. Decrease and decrease again until one reaches the state of ‘non-action’. 為學日益，為道日損，損之又損，以至於無為” (Chen 2016). Zhuangzi also inherits this idea from Laozi. Learning, in reality, involves accumulating new things upon our existing foundation, which can be considered gains in our lives. However, the Dao is nothingness. If we seek to cultivate the Dao, we must return to our original state and constantly abandon the things we possess, as these things are detrimental to the Dao. The world, including various external things and our lives, does not belong to us. Therefore, we must discard them by forgetting. This abandonment does not only refer to the abandonment of worldly troubles. In Zhuangzi’s time, while most people suffered from concerns about their safety, they also pursued material possessions, social status, and fame, all of which needed to be relinquished. Zhuangzi’s concept of forgetting encompasses everything. We must discard everything that does not belong to us, including our existence, to achieve faithful Wu Wei (無為 non-action).

“Those who chase after external things and are preoccupied with gains and losses end up losing themselves. They conform to worldly norms, follow the crowd, and lose touch with their true nature. This is a life of reversed priorities 喪己於物，失性於俗者，謂之倒置之民” (Chen 2020). Don’t lose your true self and let yourself be dominated by mundane things because of your attachment to external things, which is putting the cart before the horse. In the Dazongshi 大宗師 chapter, Zhuangzi also expresses similar views through a dialogue between Confucius and Yan Hui. Yan Hui starts by forgetting benevolence and righteousness, then moves on to forgetting rites and music, and ultimately forgets himself. He reaches a state where he “stops using his limbs, closes his eyes and ears, detaches his soul from his body, clears his mind of thoughts, and remains in harmony with the Great Dao 墮肢體，黜聰明，離形去知，同於大通” (Chen 2020). He frees himself from the constraints of the body, relinquishes acquired intelligence and talent, leaves behind the idle shell of the physical body, and dissolves accumulated knowledge, returning to the most primal state. He reaches a state of interconnectedness with all things, which Zhuangzi calls “sitting in forgetfulness坐忘”. It means transcending the limitations imposed by the body and the mind, entering a state where “the body resembles dried bones and the mind resembles extinguished ashes 形若槁骸，心若死灰” (Chen 2020). External physical form becomes insignificant, and the inner self is no longer affected by joy or sorrow in response to encounters with things or events. Having achieved the forgetting of the world, forgetting external things, and forgetting one’s own life, what happens after “self-forgetting”? “Once one has forgotten oneself, they can attain thorough enlightenment 已外生矣，而後能朝徹” (Chen 2020). They can then maintain a state of complete realization. Cheng Xuanying, a well-known Taoist figure from the Tang Dynasty, once explained this statement: “The view of life and death, the simultaneous forgetting of self and others, brings sudden enlightenment and clarity. Like the rising sun at dawn, this state is referred to as ‘Zhaoche 朝徹’. 死生一觀，物我兼忘，惠照豁然，如朝陽初啟，故謂之朝徹也” (Chen 2020). Zhaoche (朝徹) refers to a state of profound clarity and awakening. Building upon the foundation of transcending the external world, external objects, and external life, the body and soul of a person are truly unburdened. It is like the newborn sun in the early morning, shining with clarity and brightness. This sense of detachment comes after shedding the constraints imposed on us by the external world and relinquishing everything we possess, even our physical form. Through this process of detachment, our spirit finds liberation, leading to what Zhuangzi called “seeing singularity見獨”, meaning seeing the unique Dao.

The path described above is the approach that Zhuangzi offers us, where the world–subject inclusion and world–subject differentiation coexist. While cautioning against becoming obsessed with external things, Zhuangzi acknowledges that humans possess a certain capacity for transcending the mind. Zhuangzi advocates for true freedom through such methods as forgetting external things, forgetting the world, and forgetting one’s own body and life. This allows one to transcend the limitations of space and self, freely entering and leaving the world without being burdened by external attachments. This is the way of the Dao and is also Zhuangzi’s concept of “Xiaoyao 逍遙”. It is evident that Zhuangzi’s notion of freedom does not involve physically distancing oneself from the world, but rather, existing in a state of complete harmony with the world even amidst the hustle and bustle of life, where the mind can achieve a state of coexistence and transcendence with the world.

3. Discussion and Conclusions

From the perspective of Northoff’s structural ontology of the world-brain relation, this article analyzes why Zhuangzi achieved a Copernican revolution. Ideas are often interconnected, and although we can analyze them from different perspectives as later scholars do, Zhuangzi’s thoughts cannot be separated entirely. To present a clear argument, I divided the analysis into three points. However, we can also observe that the examples given in Section 2.2, Section 2.3 and Section 2.4 are not mutually exclusive. For instance, the examples in Section 2.2 can provide insights into the characteristics of Section 2.3 and Section 2.4. This observation demonstrates that the three criteria mentioned earlier are not forced interpretations or far-fetched associations with Zhuangzi’s ideas. Instead, they represent the new vitality that Zhuangzi’s thoughts embody within the framework of structural ontology.

According to the analysis in this article, we believe that the core of Zhuangzi’s metaphysics is a form of structural ontology. Zhuangzi places the individual within the context of the world, with the individual nested within the world. Thoughts are nested within the individual. His various philosophical propositions are not detached from the external world, but instead are deeply influenced by the external environment in which he exists. Indeed, Zhuangzi does not consider external phenomena as the true origin, but rather, based on his unique understanding of the relationship between the world and the individual, he places the individual in a state of dependence on the external environment. He adopts a perspective that is non-anthropocentric in nature when regarding other phenomena in the world. At the same time, Zhuangzi advocates for the individual’s capacity to obtain a sense of freedom through reflecting on their relationship with the external world. This pursuit of freedom is a central theme in Zhuangzi’s philosophy. According to Northoff’s recognition of the world–brain relationship and his criteria for the Copernican Revolution characterized by the departure from anthropocentrism, we can discern, through various analyses of Zhuangzi’s texts, that Zhuangzi achieved what Northoff refers to as the Copernican Revolution.

Northoff characterizes this revolution of Zhuangzi as a process of seeking definitive knowledge in philosophy by drawing inspiration from Zhuangzi’s teachings. He argues that Zhuangzi’s success in this endeavor is contingent upon the accurate combination of observation points, i.e., the observation point inherent within the subject and the transcendent observation point beyond the subject (Northoff 2020). Specifically, through narrative descriptions in his works, Zhuangzi presents his unique understanding of the relationship between the individual mind and the world. This understanding includes (a) Definition of the (natural) world as independent of the subject and mind. (b) Definition of the subject and its mind dependence on the world. (c) Coexistence of world-subject inclusion and world-subject differentiation. Following Zhuangzi’s line of thought, we can discern two distinct traits. Firstly, within Zhuangzi’s perspective, human consciousness possesses the ability to transcend certain specific observation points (cognitive viewpoints) and can even go beyond the collective human view, enabling individuals to engage in contemplation of a particular subject from a non-human species’ perspective, as exemplified in the story of Mao Qiang (毛嬙) and Li Ji (麗姬) mentioned earlier. Secondly, among different observation points (cognitive viewpoints), there is no absolute superiority of one over another in evaluation; otherwise, Zhuangzi would not exhibit the trait of challenging anthropocentrism. Bo Mou pointed out that Zhuangzi’s transcendence is both descriptive and prescriptive. “It is descriptive to the extent that Zhuang Zi descriptively identifies one characteristic feature of the state of conscious awareness of the persons who have achieved the Dao point of view; it is prescriptive in the sense that Zhuang Zi encourages people to take such a higher point of view, though this higher point of view resulting from reflective cultivation is not a ready-made mental state currently possessed by all of the human beings” (Mou 2008).

In conclusion, we can observe Zhuangzi’s distinctive manner of thinking by comparing the study of Eastern and Western philosophies. This thinking also offers a framework for more research comparing Eastern and Western ideologies. While two philosophical traditions belong to different cultural systems, they do not mutually exclude each other or result in one-sided influence. Instead, both can shift research perspectives on specific themes, leading to constructive engagement4 between Eastern and Western philosophies. Zhuangzi’s skepticism and contemplation on subjects, such as the world subject and human consciousness, have provided insights from Eastern philosophy for developing non-reductive neurophilosophy. Of course, the exploration of consciousness by neuroscience may also offer new perspectives on unraveling the enigmatic spiritual experiences of Zhuangzi, such as “sitting in forgetfulness 坐忘” and “Xiaoyao 逍遙”. Zhuangzi’s philosophy still provides ample room for ongoing exploration alongside scientific progress. As our understanding of the world expands through scientific advancements, we can continue to delve into the depths of Zhuangzi’s ideas and their relevance to various disciplines. The dynamic interaction between Zhuangzi’s thought and scientific inquiry opens new possibilities for enriching our knowledge and deepening our comprehension of the human experience and the natural world.