Eastern philosophy
The "Dao De Jing" ("Tao-Te-Ching," c. 4th century BCE), traditionally attributed to Laozi, and the "Nan Hua Jing" ("Zhuang Zi") are considered the key texts of the tradition. The first organized form of Taoism, the Tianshi (Celestial Masters') school arose in the 2nd century CE. Xuanxue ("deep learning", also "Neo-Taoism") was a major philosophical movement influenced by Confucian scholarship, which focused on the interpretation of the "Yijing," "Daodejing," and "Zhuangzi" and which flourished during the third to sixth centuries CE. The most important philosophers of this movement were He Yan, Wang Bi, the Seven Sages of the Bamboo Grove, Ge Hong and Guo Xiang. Thinkers like He Yan and Wang Bi focused on the deep nature of Tao, which they saw as being best exemplified by the term "Wu" (nothingness, non-being, negativity).
Classics
The earliest surviving philosophy from ancient Greece dates back to the 6th century BC, when according to Aristotle Thales of Miletus was considered to have been the first Greek philosopher. Other influential pre-Socratic philosophers include Pythagoras and Heraclitus. The most famous and significant figures in classical Athenian philosophy, from the 5th to the 3rd centuries BC, are Socrates, his student Plato, and Aristotle, who studied at Plato's Academy before founding his own school, known as the Lyceum. Later Greek schools of philosophy, including the Cynics, Stoics, and Epicureans, continued to be influential after the Roman annexation of Greece, and into the post-Classical world.