As we have seen, several periods of thought emerged in the process of Buddhist development. At least two major systems of thought, roughly speaking, closely related to what we call the primitive Buddhism and the developed Buddhism. The first is the Buddhist history of thoughts, as defined by Buddhologists such as academician Theodor Stcherbatsky (1866-1942); this division relied on different periods in the whole process of development of Buddhist thoughts. Second is the history of thoughts of Buddhist Schools, which includes several Buddhist schools; thus, you need to have time to study doctrines of each single school (e.g., Zen, Pure Land, or Tendai). Buddhism in China, for example, includes at least ten different schools, and each school also has its own system of thoughts and exclusive methods of practice.
We may generally divide the first major system, the Buddhist history of thoughts, into two major categories based on history: a) Buddhist thoughts in the primitive period and b) Buddhist thoughts in the periods of development. Buddhist thoughts in the primitive period were established on the foundational teachings of Dependent Origination and non-self, which were taught directly by the Buddha after his attainment of ultimate enlightenment. The central content of these teachings explain that all existences (dharmas) in the three worlds—senses-sphere realm, fine form realm, and formless realm[3]— are nothing but the products of inter-beings from multi-conditions. They appear in either cosmic mode (e.g., institution, existence, transformation, and destruction) or in the flux of mental transformation (e.g., birth, being, alteration, and death). In this way, all things—both the physical and the mental—are born and die endlessly, dependent on multiple conditions in the cycle of samsāra. All that is present through this Law of Dependent Origination is, therefore, impermanent, ever-changing, and without any immortal entity whatsoever that is independent and perpetual__. This is the truth of reality through which the Buddha affirmed that “whether the Buddha appears or not, the reality of dharmas is always as such.” Based upon this fundamental teaching, Buddhists built for themselves an appropriate view of personal life and spiritual practice: the liberated life of non-self—the end goal of the spiritual journey.
Although Buddhist thought in periods of development were gradually formed by various schools, two prominent systems of philosophy emerged: the Mādhyamika and the Yogācāra. Both these two philosophical systems related strictly to the primitive thought of Paticcamūpāda; however, each system has its own approach to interpretations and particular concepts. The Mādhyamika developed the doctrine of Emptiness (Śūnyatā), while the Yogācāra instituted the teaching of Mind-only (Vijñapati-mātratā), emphasizing the concept of Ālaya (store consciousness). The doctrine of Emptiness focuses on explaining that the nature of all dharmas is emptiness of essence and that all dharmas are non-self by nature and existences are but manifestations of conditional elements. Thus, when a practitioner penetrates deeply into the realm of Emptiness, he or she simultaneously experiences the reality of the non-self. However, you should remember that the concept of Emptiness used here does not refer to any contradictory categories in the dualistic sphere, such as ‘yes’ and ‘no’ or ‘to be’ and ‘not to be.’ Rather, it indicates the state of true reality that goes beyond the world of dualism. For this reason, in the canonical languages of Mahāyāna Buddhism, the term Emptiness is used as a synonym for Nirvāna. In the Yogācāra philosophy, the concept of Ālaya—the most fundamental issue of this system of thought—points out that all problems of both suffering and happiness are the very outcomes of mental distinctions (vikalpa) between subject (atman) and object (dharma), or between self and other. This mental distinction is the root of all afflictions, birth-death, and samsāra. Thus, in the path of spiritual training, a practitioner must cleanse all attachments to self as it embodies what we call the ‘I’, ‘mine’, and ‘my self’ in order to return to the realm of pure mind, which is non-distinct by nature.
Based on what has been discussed here, clearly the consistency in Buddhist thoughts—whether origin or development—is that all teachings focus on purification of craving, hatred, and attachment to self in order to reach the reality of true liberation: the state of non-self or Nirvāna.
