The first truly scientific philosopher, Aristotle was born in Macedonia, in Stagira, son of a court physician to a Macedonian king, and began living in Athens and studying at Plato's Academy at the age of 18.
He continued his studies for twenty years, until the death of Plato, after which he founded his own school of rhetoric.
He studied many sciences, and later became known as a 'panepistimon' (which means, roughly, a man of all sciences, and became the root of the Greek word for university, panepistimio).
In 342 BC, King Philip of Macedon engaged him in Macedonia as tutor of his thirteen year old son, Alexander (who would become Alexander the Great, or Megas Alexandros). Seven years later, Aristotle returned to Athens and founded his Peripatetic (Walking) Academy as part of the Lyceum, which he directed for thirteen years, during which time he also wrote philosophical works.
When Alexander died in 323 BC, the Athenians began the attempt to throw off the Macedonian yoke, and Aristotle (himself a Macedonian, and with such strong ties to the Macedonian ruler and his general) fled to the island of Evia (Euboea) to avoid conviction of charges being marshalled against him, where a Macedonian guard protected him, but he died of illness only a year later, at the age of 62.
Aristotle wrote wrote four hundred works, a veritable encyclopedia of both philosophical and scientific knowledge, forty of which have been preserved, along with fragments of another hundred or so. Most of what has been preserved of his writings is in the form of lectures for his pupils, and are quite technical, with none of the beauty of the literary prose published by Plato.
Especially valued by scholars among his works is his theory of biological order based on observation, with attention to functional adaptation of organs and instincts.
On the subject of ethics, he believed in a central God that embodied ethics and wisdom; he put a high value on intellectual work (which was, in his time and society, the province of the atristocracy, with physical work assigned to slaves).
In regard to politics, he saw three good and three evil forms of government: the kingdom, the aristocracy, and the 'republic' (which represented the power of the middle class), all of which combined oligarchy and democracy.
Tyranny, total democracy, and total oligarchy were the three evil forms of government. Aristotle saw art as a class of knowledge, and ranked it higher than knowledge of history, and formulated a theory regarding artistic creation and analyzed theoretically both epic poetry and tragedy.
The Lyceum where his Peripatetic School was situated in ancient Athens was named for the sanctuary of Lyceus Apollo found there. The grove there had been used previously for cavalry practice, and was located in the area between present-day Syntagma Square extending towards the National Gardens, its natural beauty attracting philosophers.
The socalled 'Peripatetic School', though often confused with the Lyceum (which was really the setting itself, described above), was really more of an activity, with the philosophers and their pupils walking around as they conversed, rather than sitting in one spot, just as the term 'peripatetic', from the Greek verb 'pertato' (to walk) indicates, and disciples of the school of philosophy represented by Aristotle, became known as 'peripatetics'.
All individuals to find that walking while thinking through serious problems in their lives, will understand the value of combining physical movement with analytical thought. After Aristotle's death, various schools of thought prevailed at different times, followed by a return to his works, but by the end of the 3rd century AD, the School of the Neoplatonists dominated the study of philosophy.