On Lao Tzu’s Ethics as the Inspiration and Practice of Education for Sustainable Development

: Ethics is at the core of education for sustainable development (ESD). Based on a literature review, this article discusses the inspiration and practice of Lao Tzu’s ethics in ESD. For this paper, a review was undertaken of the literature and three electronic databases were searched (Web of Science, Scopus, and Google Scholar) from 1980 to 2022 to identify relevant research topics. The literature search strategy used keywords, titles, and abstracts to search for topics, including Lao Tzu (Taoist philosophy, ethics, Daodejing) and sustainable development education (administrative leadership, curriculum, teaching). Other related articles and books are also included in the bibliography. It was concluded that Lao Tzu’s “the Tao way follows nature” and “non-contention” can build a harmonious society; practicing “minimalism” can help achieve economic sustainability; and the concept of “the birth of the unborn” pioneers the coexistence of human beings and nature. Schools that practice ESD can apply Lao Tzu’s ethics to establish a sustainable and harmonious leadership relationship in the way of saints, and adopt a teacher–student interaction model that follows “the supreme good is like water” principle to establish ethical literacy and introduce ethics courses that are autonomous, interactive, and for the common good. Therefore, the exploration of Lao Tzu’s ethics allows Eastern thought to be at the core of the ethics and values of ESD, and provides practical insights into school administration, teaching, and curriculum implementation.


Introduction
Since the Industrial Revolution in the 18th century, the world has been oriented toward economic growth. As a result, it is now facing many serious environmental issues, such as global warming, depletion of natural resources, spread of diseases, uneven distribution of food, and increasing poverty. Although governments and non-governmental organizations are working to tackle the world's current environmental crisis and promoting environmental education, they must also address social and economic issues such as gender equality, health and hygiene, the wealth gap, hunger, and corporate responsibility [1][2][3]. Venerable Sheng Yen, a renowned religious figure, states that the current rapid progress of science and civilization will cause unimaginable depletion of the Earth's resources and damage to the environment. Therefore, we should start from the transformation of human values and the purification of the human mind [4]. In Buddhism, anituh and sunya are the basic phenomena of the world, and duhkha is the individual's fundamental feeling and anatman attitude. Buddhist scriptures show that there are five natural laws in the universe, namely, the physical law, biological law, psychological law, moral law, and causal law. Therefore, one of the Five Precepts of Buddhism is the precept against killing, i.e., being kind to all living things, loving life, and not killing living beings. In the face of nature, it advocates aparigraha and simplicity; in the face of the environment and water resources, it demands cleanliness and cleanliness with public morality. This is a value that human beings must reestablish from the moral and spiritual level [5]. From the core point of view of philanthropy, Christianity is the conservation of natural resources that arises from humanitarianism and the romantic view of nature in the face of concerns about the long-term use of the natural environment [6]. Pope St. John Paul II's 1990 World Day of Peace Message clearly stated that the current ecological crisis involved ethics and morality, and the solution was the sincere cooperation of all mankind [7]. The ecological ethics thought of Islam is a world view that attaches importance to the harmony of the whole and emphasizes the unity of man and nature. Islamic culture values harmony and balance between man and nature, and takes care of natural objects with a sense of universal love [8]. Based on the thought of the unity of nature and human beings, Chinese Confucianism has expanded from the thought of moral concern for social relations between people to the natural ecological view of caring for life with benevolence as the core idea [5,9]. This is also mentioned in the chapter of King Hui of Liang of Mengzi: "Grain and aquatic products will not run out, and wood will not run out. If this is the case, people will not be dissatisfied with feeding the living and burying the dead. The people are not dissatisfied with feeding the living and burying the dead, which is the beginning of the kingly way." [10]. Taoism is one of the most well-known Eastern philosophies in the Western world. For the ethics of Lao Tzu in Taoism, principles such as the law of nature, doing nothing but doing everything, the supreme good is like water, and Tao of sages are the ethical values of harmony between man and nature, man and man, and man and all things, in addition to the thinking values of sustainable development of nature and human beings [11][12][13][14]. The Tbilisi Declaration [15] in 1977 and the World Conservation Strategy [16] of 1980 indicate that the fundamental task of environmental education is to develop new ethics for the harmonious coexistence of human beings and the natural world, and to promote ethical attitudes and behaviors through education. As such, the fundamentals and core of environmental education are always ethics and values [17,18].
Since 1972, when the United Nations convened various international conferences to reflect on the problems of people and the environment, the concept of sustainable development (SD) has been recognized and developed, highlighting that education is a major pathway for human beings to move toward such development [19][20][21][22][23]. The concept of environmental education and education for sustainable development (ESD) are mutually inclusive, but ESD, in contrast to environmental education that only emphasizes human attitudes toward the environment, is an educational tool and strategy developed to address environmental, economic, and social unsustainability [22,[24][25][26]. Importantly, whether environmental education is a part of ESD, or whether the relationship between the two is equivalent or a two-axis symbiotic framework, ethics are central to both types of education [27], because, to build a sustainable society, the society must reexamine its values [28]. Just as ethics and values should be fundamental to environmental education, they are central to ESD [29,30].
In the case of Western environmental ethics, the long-standing concept of anthropocentrism [31], coupled with the supremacy of scientism and the persistent pursuit of profit maximization by capitalism, has led to increasingly serious ecological problems and the inability to strike a balance between social, economic, and environmental development. In contrast, in Chinese Taoism, as early as over 500 years ago, Lao Tzu's Tao Te Ching explained in the way of "the birth of the unborn" that the root of all things in Heaven and Earth is Tao, which realizes the equal status and rights of all things therein [32]. Many scholars have used Lao Tzu's Taoism to examine environmental ethics [5,17,[33][34][35][36][37][38][39][40], showing that his ideas correspond to "life-centered ethics", "ecocentric ethics", "deep ecology", and other environmental ethics [41]. Lao Tzu's ethics have their own uniqueness and make a pioneering contribution to ESD. He used the ethics of "the Tao way follows nature", "letting things take their own course", "emptiness", "the supreme good is like water, which nourishes all things without trying to", and "Tao of saints" as harmonious and consistent ethics. He also proposed the value of thinking about the SD of all things in Heaven and Earth, in addition to people in the world, to avert the chaos of the country and move toward a society of common good and common prosperity [38,42,43].
It is worthwhile to further explore how these connotations can serve as a reference for modern ESD. For this paper, a review was undertaken of the literature and three electronic databases were searched (Web of Science, Scopus, and Google Scholar) from 1980 to 2022 to identify relevant research topics. These articles explore the relationship between Lao Tzu's ethics and sustainable development education, taking Lao Tzu's thoughts as the core of sustainable development education ethics. The literature search strategy used keywords, titles, and abstracts to search for topics, including Lao Tzu (Taoist philosophy, ethics, Daodejing) and sustainable development education (administrative leadership, curriculum, teaching). Other related articles and books are also included in the bibliography, which has a total of nearly 130 articles. We use Lao Tzu's ethics as the inspiration and practice of ESD and lay a foundation for a deeper understanding.

Current Ethics of SD
Changing with the times, environmental ethics has expanded from anthropocentric ethics into life-centered and ecocentric ethics [44]. Environmental paradigms are also gradually expanding from ecological conservation to social and political levels [5,45]. The main belief of anthropocentrism is that human beings have superiority over all things in nature and that there is no ethical relationship between all things in nature and human beings. The belief of life-centered ethics is that human beings should care for the existence of individual life with morality and value the equality and respect of all things in nature. Ecocentric ethics stresses the intrinsic value of the natural world, the moral and ethical relationship of the ecosystem as a whole, and the transfer of environmental paradigms [30]. Environmental ethics, however, encompasses only environmental ecology, not the unique social and economic activities of human beings. ESD comprises environmental, social, and economic facets; thus, the ethics of SD must solve the problem of personal self-identity and related design problems in modern society [46]. The accomplishment of sustainable development goals (SDGs) must clarify the environmental beliefs and attitudes of human beings [29]. Ethics are originally defined as the moral standards of human interaction and involve individual norms [47,48]. Ethics play two major roles in SD: to settle conflicts of values and to define a new social paradigm [49]. Sustainability is the practice of crossdisciplinary integration, and systemic collaboration across disciplines should be based on the consistency of the ethics of ESD [50]. As such, it is essential to establish an ethical framework for SD develop a more holistic and deeper concern for the moral and ethical development of people and society, in addition to people and economic development.
In 1991, the United Nations Environment Program (UNEP), International Union for Conservation of Nature (IUCN), and World Wide Fund for Nature (WWF) [51] published the book "Caring for the Earth: A Strategy for Sustainable Living" to devise world ethics centered on human beings and conservation and development. This comprises the following elements: (1) Human society and nature are united. (2) Individuals have rights to survival, freedom and security, freedom of thought, religion, assembly and association, participation in public affairs, and education, and are protected and respected. (3) Human development should preserve ecological integrity and diversity, and be free from cruelty, suffering, and unnecessary killing. (4) Everyone should share the benefits and costs of resource use in a fair manner, and use resources in an efficient and sustainable manner. (5) Valuing the needs and rights of future generations, each generation should pass on environmental resources that are diverse and productive. (6) Protecting the rights of human beings and nature is a worldwide responsibility that transcends time, space, culture, and ideology [30]. The above are the basic elements of ethics for SD. The ethical issue of SD is how to live in harmony and balance with one's contemporaries, future generations, and nature in terms of values, attitudes, and behaviors [24,52,53].This is the moral relationship between human beings and their contemporaries, that between human beings and their future generations, and that between human beings and nature. This is also an ethical facet of triple relevance, differing from environmental ethics, which focuses on the relationship between human beings and nature [54]. ESD lacks a clear ethical framework [55]. As a result, there is a need for a systematic approach to the norms of human and social, environmental, and economic life, and for guidelines for action. In the way of education, the ethics of ESD that are consistent with equality, respect, freedom, education, and social justice have been established with the aim of a holistic view of human development and economic activity, harmonious relationships in human society, and SD between human beings and the environment. Therefore, this article analyzes the ethics in Lao Tzu's Tao Te Ching to further explore its nature, ethical framework, and principles of practice as the ethics of ESD.

Lao Tzu's Ethics in Tao Te Ching
Lao Tzu's Tao Te Ching is rich in philosophical ideas. This article explores the core spirit of his philosophy of "letting things take their own course", "emptiness", "the supreme good is like water, which nourishes all things without trying to", and "to not contend for", and grasps the essence of "the Tao way follows nature" and the ethics of ESD. The Tao Te Ching starts with "letting things take their own course", which is not "laissezfaire", but rather the removal of the self-centered thoughts of human beings that are selfish and delusional, thereby achieving a state of "letting things take their own course, yet everything is accomplished" [56,57]. People can "do" something, but they have to take "letting things take their own course" as the foundation, so as to achieve and "yet everything is accomplished." Following "the course of nature" is "letting things take their own course." [58,59]. Another philosophical viewpoint of Lao Tzu is "I try my best to make the silence of the mind reach the extreme, so that the quietness of life remains unchanged. All things flourish together, and this study examines the reason for their reciprocity" (Tao Te Ching, Chapter 16). Lao Tzu's practical work of "emptiness" is not deadly emptiness, but the removal of selfish desires and distracting thoughts, so that the mind can be clear and return to emptiness and all things can grow freely in Heaven and Earth, living out their original appearance [56,57].
Lao Tzu further used water as an analogy to learn the humility, non-contention, and softness of water. As he stated, "The persons or things that have the highest excellence are just like water. They benefit all things instead of contention. They stay at the lowest place which all men dislike. So this kind of persons and things are very close to 'Tao'" (Tao Te Ching, Chapter 8). The nature of water contains the profound philosophy of "Tao". The clarity, softness, humility, and inclusiveness of water have achieved the harmony and unity of all things in Heaven and Earth [60,61]. Lao Tzu stated: "Humans should take their law from the Earth; the Earth follows the trail of Heaven; Heaven follows the trail of Tao; the law of the Tao is its being what it is" (Tao Te Ching, Chapter 25). He used "the Tao way follows nature" to promote his main ideas as follows. Tao is the source of nurturing all things in Heaven and Earth, Tao follows the law of nature, nature is the nature and spirit of Tao, and all things in Heaven and Earth develop based on the law of their nature, showing a clear and adaptive state of virtue and wisdom [62][63][64].
The term "nature" has different meanings in the Tao Te Ching and Western theories. The Western term "nature" is a type of materialism, the world of material phenomena studied by natural science. "Nature" in Lao Tzu's Taoist thought contains the open concept of "holding a free and unfettered idea", "harmony without harm", and "openness without hindrance", which is an open concept of freedom, independence, the harmony between Heaven and Earth, and the harmony between things and "me" [65,66]. Therefore, the thought in Tao Te Ching highlights the relationship between human beings and all things by removing selfishness and self-centeredness, takes the attitude and method of noncontention and inaction to accomplish everything, and learns the humility, softness, and inclusiveness of water to promote harmony [67].

Context and Ways of ESD
The concept of SD originated in the 1980s and was explicitly defined in The Brundtland Report [53] in 1987 as "development that meets the needs of the present without compromising the ability of future generations to meet their needs." In 1988, the United Nations Educational, Scientific, and Cultural Organization (UNESCO) proposed the term "Education for Sustainability" (EfS) after considering the goals, nature, tasks, and content of environmental education, which is the earliest initiative of UNESCO's idea of ESD [68]. Proposed at the 1992 World Summit in Rio de Janeiro, Agenda 21 [69] clearly identified three key aspects: promoting education, raising public awareness, and strengthening training. This Agenda explicitly identifies education as a necessary means of SD [21,23]. Subsequently, in 1994, the United Nations Commission on Sustainable Development (CSD) put forward the environmental, population, and development-based EfS program centering on human harmony and international creativity. In line with Agenda [71] adopts a clear educational framework to set forth policies for each of the 17 SDGs, and proposes educational strategies and actionable issues on how to incorporate formal and non-formal education from three major aspects-cognition, skills, and affection-in addition to the eight principal competencies [72].
In summary, international organizations have developed the concept of SD in the hope of redressing the current imbalance in development patterns and striking a balance between human development needs and the carrying capacity of nature. Education is the core of the success of SD; that is, we can achieve sustainable environmental, social, and economic development through the process of education [24]. From the perspective of the development context of ESD, it is hoped that the unsustainable problems arising from the environment, society, or economy will lead to changes therein through changes in the education model [72]. The purpose of ESD is to promote an understanding of the relationships between people and people, people and the environment, and people and society, and that education is imperative to promote sustainable environments, societies, and economies [73]. ESD aims to change learners' understanding and awareness of sustainability, and to offer training opportunities to enhance effectiveness, thus promoting positive sustainability behaviors [69,74]. ESD must consider the three dimensions of sustainability, i.e., the environment, society (including culture), and economy, and embrace the principles of fairness, sustainability, and commonality [75]. The principle of fairness emphasizes fairness within and between generations, and in the distribution and use of resources, corrects the global phenomenon of rich and poor disparity and polarization, makes the eradication of poverty a special priority in the process of sustainable development, and grants equal rights to development to all present and future generations to meet basic needs. The principle of sustainability advocates sustainable economic growth based on the protection of the Earth's natural system. There must be restrictions while meeting demands; that is, development contains the concept of constraints. The development or demand of the human economy and society cannot exceed the carrying capacity of the environment. The principle of commonality is that mankind and the Earth as a whole are a community with a shared future and jointly realize the goal of sustainable development. We should recognize the integrity and interdependence of the Earth through global actions, uphold the principle of common fairness and sustainability, and implement the goal of sustainable development according to the particularity of regional culture [76,77].The ESD shifts from traditional education concentrated on imparting knowledge, attitudes, and values for the purpose of behavior change, to a modern practice that focuses on understanding and seeking the root causes of problems, encouraging value clarification, changing ideas, influencing decision making and action, in addition to fairness and justice, and valuing structural and institutional changes [78]. Based on the three directions and three principles of SD, EfS was developed by re-integrating the goals, nature, tasks, and contents of environmental education. Through the participation of representatives, experts, and scholars from many countries in many international conferences, discussions, and studies, a consensus was formed, and a number of declarations, agenda documents, and conference proceedings were published, thereby forming ESD.

Inspiration of Lao Tzu's Ethics for ESD
As previously mentioned, the concept of SD is a review and rethinking of the wrong direction of human development in the past, in the hope of correcting the current imbalanced development pattern and striking a balance between the needs of human development and the carrying capacity of nature. In contrast to Lao Tzu's background at a time of political turmoil and social unrest, when the Zhou Dynasty's culture of rites and music has decayed and is in a disastrous state [79,80], the world today is facing complex social, economic, and environmental crises, and is facing the same dilemma as Lao Tzu's social background. In writing the Tao Te Ching, Lao Tzu offered wise advice, hoping to change the chaotic situation of political instability and unhealthy living conditions and to build a better and ideal society. Sharing the same goal of developing the ethics of ESD today, he expected to reflect on the past disharmony and imbalance between people and people, people and society, and people and the environment, and to correct human ethics through education [38]. Therefore, his ethics can be used as the basis for the ethics of SD. Lao Tzu's Taoist ethics of "letting things take their own course, yet everything is accomplished" aims to educate people to correct their subjective state of mind, so that the accomplishment of "letting things take their own course" and "following the course of nature" can be further put into practice in their lives. With the attitudes of "letting things take their own course" and non-contention of saints, learning the essence of water, which symbolizes nature's softness, humility, and benefit to all things, is a model and ethical thought for the interaction between all things in Heaven and Earth (economic, social, and environmental aspects). This agrees with the philosophical spirit and practical principles behind ESD, and is one of the paths chosen to inspire human beings to put ESD into practice [62,81,82].
The ethics in the Tao Te Ching inspires ESD as a blueprint for realizing a vision of equality and common good between human beings and society, the economy, and nature [81][82][83][84]. SD comprises three principles: fairness, sustainability, and commonality. First, to construct a harmonious society with the attitudes of "the Tao way follows nature", "letting things take their own course and non-contention", and "emptiness", we should reflect on the development of contemporary human interaction from the smallest internal thoughts and external behaviors of individuals, to the largest national society and the world. The mainstream values of convenience, speed, profit, desire, and material supremacy have neglected the inner beauty of individuals [34,85,86]; as Lao Tzu mentioned, "the colorful colors make people dazzled, the noisy tones make people lose their hearing, the rich food makes people lose their taste, indulging in hunting makes people crazy" (Tao Te Ching, Chapter 12). The next level is "the creation of thoughts and ideas", such as "racism", "national consciousness", "feudalism", and other thoughts and ideas that affect the world; as the saying goes, "When the Tao prevails in the world, they send back their swift horses to (draw) the dung-carts. When the Tao is disregarded in the world, the war-horses breed in the border lands" (Tao Te Ching, Chapter 46). If a king believes that everything in the world should be unified in his own hands and starts a war, the resulting misery will be unbearable as the people will not be able to live and families will be separated [41,56,87], which is indeed the case in the current war between Russia and Ukraine. Therefore, ESD should begin with the cultivation of the individual's body and mind, the elimination of selfish desires, the calm of the mind, the saint's ways of "letting things take their own course" and non-contention, and the learning of softness, humility, and the interactive mode of benefiting all things like water, to create a harmonious and impartial principle of fairness. Further, it should begin with the ethical attitudes of "the Tao way follows nature", "non-contention", and "emptiness", to meet the principle of sustainability, and follow the principle of "the Tao is unique in that the Tao itself contains both yin and yang, which intersect to form a state of proper balance in which all things arise." We believe that all things in Heaven and Earth share a common nature and a common origin, and that the principle of commonality should be achieved [85,88]. We call for ESD to start from personal inner beauty, to practice social harmony, fairness, and justice, and to create the concept of SD for generations, so as to achieve the goal of ESD through formal or informal education by means of regional cooperation and international cooperation [89].
To achieve economic and SD through "minimalism", the UNDESD calls for a systematic approach to a sustainable economy, realizing the limits and risks of economic growth, and examining social and environmental impacts. As such, human beings should take the importance of a circular economy into account with a minimalist ethical mindset and attitude [38,90]. Lao Tzu stated, "But I have three precious things which I prize and hold fast. The first is gentleness, the second is economy, and the third is shrinking from taking precedence of others. With that gentleness I can be bold, with that economy I can be liberal, . . . by his (very) gentleness protecting him" (Tao Te Ching Chapter 67). Lao Tzu's "economy" from the ethical thought of practice is to tell people to meet the basic needs of mankind and suppress the unlimited desires of the body and mind, not be extravagant and wasteful in material terms, not to pursue excessive enjoyment, and to strive to achieve minimalism of "what you want is not necessarily what you need" [79,91,92]. Therefore, in the practice of ethical actions, human beings are reminded that, when developing the economy and exploiting the resources of the Earth, they should not do so to excess and cause damage to the ecological environment and disturb the original balance. We should be "compassionate" and consider all creatures in the world, sympathize with the living conditions of animals and plants, and moderate our desires, so as to secure life and growth in nature to create a balance between economic growth of human beings and SD of the environment [60,93].
In terms of the natural environment, Lao Tzu's ethical concept of "the birth of the unborn" pioneers the coexistence of human beings and nature, realizes no direct intervention in all things, and provides an environment suitable for the growth of all things, enabling all things to develop adaptively [34]. The environmental ethics developed by his "Tao" corresponds to "life-centered ethics" and "ecocentric ethics", which also believe that all living creatures have their own natural values and can achieve self-fulfillment, that human beings and living creatures are equal in status and have "intrinsic values" and the right to "self-realization", and that the principles of non-harm and non-molestation should be adopted for living creatures [36,94,95]. We argue that the meaning of Lao Tzu's environmental ethical concept of "the birth of the unborn" is to open up the source and smooth the flow, and to allow things to grow on their own, and not to dominate or control the environment; as such, all living things can grow and realize themselves, and people and the environment can coexist and co-prosper in harmony, and the ecological environment can develop in a stable, balanced, and sustainable way [35,96,97].

Promoting the Practice of ESD through Lao Tzu's Ethics
Ethics is a part of moral philosophy, and concerns the value questions and the implementation of behaviors [98]. Ethics emphasizes not only norms, but also relations, and is a criterion of value in relations [99]. Ethics is a norm of value in a relationship. Social ethics underlines group norms in social relations [53]. The sociologist Georg Wilhelm Friedrich Hegel also implies that ethics is an objective will embodied in the family, society, and nation [100]. The ethics of ESD is being valued in school education, and ethics, rather than a separate subject, is integrated into the curriculum of various fields [101]. SD highlights the balanced and harmonious development of the environment, society, and economy. The ethics of ESD is the process of education that regulates and evaluates how the content is carried out by stakeholders to achieve the goal of SD [46]. As societies change and postmodernism becomes more decentralized, anti-authoritarian, and pluralistic, in addition to the cultural differences across countries, regions, and localities, the relationships between people and members of school groups are deeply affected, making it hard to establish harmonious relationships with each other and to fully understand or develop the values that individuals, communities, and nations should have. The ethical problems faced by schools are related to the challenges and disruptions of the harmonious relationships in schools, in addition to the difficulties in establishing and maintaining such relationships [102,103]. We can take the philosophical thinking of Lao Tzu's core spirit of "saints always remain unselfish", "the supreme good is like water, which nourishes all things without trying to", "minimalism", "the opposite", and "non-contention" as the basis for the practice of ESD, and integrate the diverse cultures and values of postmodernism, to organize the practice of ESD with ethical connotations and implement it in school administration, curricula, and teaching.

Administrative Leadership for ESD Should Emphasize the Way of the Saint
Leadership theories evolved from trait and behavior theories to situational authority theories in the early and late 20th century, respectively, to modern emerging leadership theories such as moral, value, cultural, service, and empowerment leadership [104]. School leadership is a moral craft. As a matter of fact, school education includes moral education, and school is a moral community. The principal must set an example, improve moral practice, and subtly influence the members of the school organization, so that they can establish correct values, have a sense of responsibility and obligation, and create the sustainable development of the school. Therefore, the principal is the spokesperson of morality [105,106]. School administrators and leaders who promote ESD should implement it at a moral level, and principals and teachers should lead by example in implementing environmental education and SDGs to inspire students, parents, and community residents. This is the realization of Lao Tzu's saying, "The saint has no invariable mind of his own; he makes the mind of the people his mind. To those who are good (to me), I am good, and to those who are not good (to me), I am also good, and thus (all) get to be good. To those who are sincere (with me), I am sincere, and to those who are not sincere (with me), I am also sincere, and thus (all) get to be sincere....". Furthermore, the practice of values leadership in ESD is in line with his next statement: "...The saint has in the world an appearance of indecision, and keeps his mind in a state of indifference to all [107,108].The people all keep their eyes and ears directed to him, and he deals with them all as his children" (Tao Te Ching, Chapter 49). Lao Tzu's ethical thinking emphasizes that the saint should face all things in Heaven and Earth with an open and selfless compassion, namely, a manifestation of "virtue of compassion." [109]. Leaders in ESD must not only have a compassionate and selfless heart, but also have their vision and thoughts on ESD be consistent and resonate with the beliefs and values of the people they are leading, so that they can realize the value leadership of "the wishes of the people are always in my heart." [110,111].

Programs on ESD Should Present "The Tao Way Follows Nature"
Lao Tzu's ethical thinking emphasizes natural inaction, whereas Western naturalism argues that nature has its own laws. We need to rethink the relevance of nature to important issues such as society, humanity, morality, politics, law, and education. There are commonalities between the two. Rousseau's view of education values the natural development of children, avoids external suppression or distortion, uses nature as a teaching material, returns to the children themselves, satisfies students' interests and needs through nature-based activities, and emphasizes the connection between humans and nature [112]. Therefore, in the promotion of programs on ESD, both formal and non-formal education must use the philosophy of "the Tao way follows nature" to inspire the ethical attitudes of teachers and learners toward ESD. It is only by starting from the heart that we can build a spontaneous, voluntary, and naturally internalized ethic of SD, without the need to be bound by others or by the external layers of the law [113][114][115]. Moreover, Chapter 64 of the Tao Te Ching states, "The big tree grows from the tiny sprout; the nine-story high platform is built from every pile of soil; the thousand-mile journey starts from the first step under the feet." This indicates that his thought advocates the importance of unpreparedness, the subtle, and the orderly [112]. Its application to the design of educational curricula should be from the simple to the deep, step by step, and the teaching and teaching materials should be designed according to individual needs [116,117]. Consequently, Lao Tzu's ethical practice emphasizes inner beauty, and by embodying such practices as "following the course of nature and letting things take their own course", "keeping the path and cultivating virtue", "being born without having, being for and not serving", "simple life", "to achieve the ultimate emptiness, to keep quiet and stubborn", and "aesthetics of meditation", "the Tao way follows nature" can be internalized as the main feature of the ideal practice of life. When facing social, economic, and environmental problems, it is natural to seek answers from the inner mind, rather than always looking for more external solutions. When faced with such problems, one can naturally look to the inner mind for answers rather than to the outer world for more material satisfaction [118,119]. When programs on ESD are integrated with the principles of Lao Tzu's ethical thinking, more systematic and holistic "spiritual therapy" and "physical practice" can be formulated, which agree with such programs in educational psychology [115].

Educators in SD Should
Master the Teaching Strategies of "Emptiness and Gentleness", "The Supreme Good Is Like Water", and "Mutual Transformation and Promotion" Early childhood is an important stage in human development, and educational experiences during this period affect cognitive development, socio-emotional state, and mental abilities [120]. Therefore, the methods of education are very important. As indicated in the Book of Rites by Xue Ji, teaching is a growth process in which teachers and students interact mentally; that is, teaching benefits teachers as well as students. For ESD to be effective, teachers should change the way they teach students [121]. The teaching and learning approach to ESD plays a critical role, and effective teaching strategies can contribute to the delivery of programs on ESD [122]. It is suggested that problem-based teaching is the best strategy for guiding students' learning in ESD, the teaching method of lecturing should be avoided, and students should be made the main subject of inquiry learning and the master of the classroom [75,123].Teachers guiding students to become the subjects of learning is a type of dignity and respect for human nature, and human dignity is the space for teacherstudent interaction and the expression of Lao Tzu's ethical thought that "the supreme good is like water" and "with gentleness one can be bold." [124]. Educator Rousseau advocates human freedom and equality. In a state of nature, all people enjoy their natural rights, and, moreover, education should be implemented in a state that conforms to the laws of nature, allowing children to develop freely through practical life and physical experience. This concept is in line with Lao Tzu's philosophy of "the Tao way follows nature." His philosophy is a valuable inspiration for teaching strategies in ESD. Teachers should view the teacher-student interaction with a state of mind of "emptiness and gentleness" and refrain from negative practices of indoctrination and imposition [125]. Through open, fluid, and soft teacher-student interactions, resembling water, and a respectful attitude toward teacher-student interactions, students shift from being passive dependents to independent learners in a mutually subjective relationship, creating new value possibilities with their own abilities, leaping out of the established value frontier, and embarking on a path of continuous "becoming" [111,126,127].

Conclusions
This article discusses the ethical nature of ESD, with Lao Tzu's ethical ideas of "following the course of nature" and "letting things take their own course", emptiness, non-contention, and "the supreme good is like water" as its ethical essence. With this as the key to education, ESD has been put into practice in schools. In terms of administration, ESD emphasizes that leaders should attach importance to personal moral cultivation and lead through ethics, using the virtues of the saints as a model [128]. Leaders should establish a visionary goal of education for sustainable development in schools, organize a community of teachers, and link resources to achieve the ultimate goal of education for sustainable development for the well-being of all mankind. Importance should also be attached to the environmental ethics of equality in all things, the social cosmopolitanism of harmony and unity, and the view of the circular economy of simplicity without aggression [110,111]. The implementation of teaching and curriculum planning should gradually progress from the simple to the deep, and the teaching and teaching materials should be designed according to individual needs [116,117]. We use the philosophy of "the Tao way follows nature" to inspire teachers and learners to adopt ethical attitudes toward SD, and to inspire teachers and students to build ethical literacy and ethics courses that are autonomous, interactive, and for the common good from the heart of the individual [113,118,119]. For teacher-student relationships and teaching strategies, teachers are inspired to look at teacher-student interactions with a state of mind of "emptiness and gentleness", and to learn from "the supreme good is like water". Teachers should thus design an open, fluid, and soft model of teacherstudent interaction and conversation, shaping teachers and students into dynamic agents of mutual subjectivity in teaching and learning [111,[125][126][127]. Overall, the exploration of Lao Tzu's ethics as the essence of ESD allows Eastern thought to be at the core of the ethics and values of ESD, and provides insights into its possible challenges and practical inspirations in school administration, teaching, and curriculum implementation.

Conflicts of Interest:
The authors declare no potential conflict of interest with respect to the research, authorship, and/or publication of this article.