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).
Ancient Greek literature
Of all the classical philosophers, however, Socrates, Plato, and Aristotle are generally considered the most important and influential. Socrates did not write any books himself and modern scholars debate whether or not Plato's portrayal of him is accurate. Some scholars contend that many of his ideas, or at least a vague approximation of them, are expressed in Plato's early socratic dialogues. Meanwhile, other scholars have argued that Plato's portrayal of Socrates is merely a fictional representation intended to expound Plato's own opinions who has very little to do with the historical figure of the same name. The debate over the extent to which Plato's portrayal of Socrates represents the actual Socrates's ideas is known as the Socratic problem.
Plato expressed his ideas through dialogues, that is, written works purporting to describe conversations between different individuals. Some of the best-known of these include: "The Apology of Socrates", a purported record of the speech Socrates gave at his trial; "Phaedo", a description of the last conversation between Socrates and his disciples before his execution; "The Symposium", a dialogue over the nature of love; and "The Republic", widely regarded as Plato's most important work, a long dialogue describing the ideal government.