When Plato died in 347 bc, Aristotle moved to Assos, a city in Asia Minor, where a friend of his, Hermias (died 345 bc), was ruler. There he counseled Hermias and married his niece and adopted daughter, Pythias. After Hermias was captured and executed by the Persians, Aristotle went to Pella, the Macedonian capital, where he became the tutor of the king's young son Alexander, later known as Alexander the Great. In 335, when Alexander became king, Aristotle returned to Athens and established his own school, the Lyceum. Because much of the discussion in his school took place while teachers and students were walking about the Lyceum grounds, Aristotle's school came to be known as the Peripatetic ('walking' or 'strolling') school. Upon the death of Alexander in 323 bc, strong anti-Macedonian feeling developed in Athens, and Aristotle retired to a family estate in Euboea. He died there the following year.
Aristotle, like Plato, made regular use of the dialogue in his earliest years at the Academy, but lacking Plato's imaginative gifts, he probably never found the form congenial. Apart from a few fragments in the works of later writers, his dialogues have been wholly lost. Aristotle also wrote some short technical notes, such as a dictionary of philosophic terms and a summary of the doctrines of Pythagoras. Of these, only a few brief excerpts have survived. Still extant, however, are Aristotle's lecture notes for carefully outlined courses treating almost every branch of knowledge and art. The texts on which Aristotle's reputation rests are largely based on these lecture notes, which were collected and arranged by later editors.
Among the texts are treatises on logic, called Organon ('instrument'), because they provide the means by which positive knowledge is to be attained. His works on...