Aristotle (Aristoteles) was a Greek scientist and philosopher. Along with Plato, he is often considered to be one of the two most influential philosophers in Western thought.
Aristotle was born at Stagira, a Greek colony on the Macedonian peninsula Chalcidice in 384 BCE. His father, Nicomachus, was court physician to King Amyntas of Macedonia. It is believed that Aristotle's ancestors held this position under various kings of Macedonia. Aristotle was probably influenced by his father's medical knowledge; when he went to Athens at the age of 18, he was likely already trained in the investigation of natural phenomena.
From the ages of 18 to 37 Aristotle remained in Athens as a pupil of Plato and distinguished himself at the Academe. The relations between Plato and Aristotle have formed the subject of various legends, many of which depict Aristotle unfavourably. No doubt there were divergences of opinion between Plato, who took his stand on sublime, idealistic principles, and Aristotle, who even at that time showed a preference for the investigation of the facts and laws of the physical world. It is also probable that Plato suggested that Aristotle needed restraining rather than encouragement, but not that there was an open breach of friendship. In fact, Aristotle's conduct after the death of Plato, his continued association with Xenocrates and other Platonists, and his allusions in his writings to Plato's doctrines prove that while there were conflicts of opinion between Plato and Aristotle, there was no lack of cordial appreciation or mutual forbearance. Besides this, the legends that reflect Aristotle unfavourably are traceable to the Epicureans, who were known as slanderers. If such legends were circulated widely by patristic writers such as Justin Martyr and Gregory Nazianzen, the reason lies in the exaggerated esteem Aristotle was held in by the early Christian heretics, not in any well-grounded historical tradition.
After the death of Plato (347 BCE), Aristotle went with Xenocrates to the court of Hermias, ruler of Atarneus in Asia Minor, and married his niece and adopted daughter, Pythias. In 344 BCE, Hermias was murdered in a rebellion, and Aristotle went with his family to Mytilene. Then, one or two years later, he was summoned to his native Stagira by King Philip II of Macedon to become the tutor of Alexander the Great, who was then 13.
Plutarch wrote that Aristotle not only imparted to Alexander a knowledge of ethics and politics, but also of the most profound secrets of philosophy. We have positive proof that Alexander profited by contact with the philosopher, and that Aristotle made prudent and beneficial use of his influence over the young prince. Due to this influence, Alexander provided Aristotle with ample means for the acquisition of books and the pursuit of his scientific investigation, and it is quite likely that Alexander the Great's renowned military ability can be traced, at least in part, to his relationship with Aristotle.
In about 335 BCE, Alexander departed for his Asiatic campaign, and Aristotle, who had served as an informal adviser (more or less) since Alexander ascended the Macedonian throne, returned to Athens and opened his own school of philosophy. He may, as Aulus Gellius says, have conducted a school of rhetoric during his former residence in Athens; but now, following Plato's example, he gave regular instruction in philosophy in a gymnasium dedicated to Apollo Lyceios, from which his school has come to be known as the Lyceum. (It was also called the Peripatetic School because Aristotle preferred to discuss problems of philosophy with his pupils while walking up and down -- peripateo -- the shaded walks -- peripatoi -- around the gymnasium.)
During the thirteen years (335 BCE-322 BCE) which he spent as teacher of the Lyceum, Aristotle composed most of his writings. Imitating Plato, he wrote "Dialogues" in which his doctrines were expounded in somewhat popular language. He also composed the several treatises (which will be mentioned below) on physics, metaphysics, and so forth, in which the exposition is more didactic and the language more technical than in the "Dialogues". These writings show to what good use he put the resources Alexander had provided for him. They show particularly how he succeeded in bringing together the works of his predecessors in Greek philosophy, and how he pursued, either personally or through others, his investigations in the realm of natural phenomena. Pliny claimed that Alexander placed under Aristotle's orders all the hunters, fishermen, and fowlers of the royal kingdom and all the overseers of the royal forests, lakes, ponds and cattle-ranges, and Aristotle's works on zoology make this statement more believeable. Aristotle was fully informed about the doctrines of his predecessors, and Strabo asserted that he was the first to accumulate a great library.
During the last years of Aristotle's life the relations between him and Alexander the Great became very strained, owing to the disgrace and punishment of Callisthenes whom Aristotle had recommended to Alexander. Nevertheless, Aristotle continued to be regarded at Athens as a friend of Alexander and a representative of Macedonia. Consequently, when Alexander's death became known in Athens, and the outbreak occurred which led to the Lamian war, Aristotle shared in the general unpopularity of the Macedonians. The charge of impiety, which had been brought against Anaxagoras and Socrates, was now, with even less reason, brought against Aristotle. He left the city, saying (according to many ancient authorities) that he would not give the Athenians a chance to sin a third time against philosophy. He took up residence at his country house at Chalcis, in Euboea, and there he died the following year, 322 BCE. His death was due to a disease from which he had long suffered. The story that his death was due to hemlock poisoning, as well as the legend that he threw himself into the sea "because he could not explain the tides," is without historical foundation.
Very little is known about Aristotle's personal appearance except from hostile sources. The statues and busts of Aristotle, possibly from the first years of the Peripatetic School, represent him as sharp and keen of countenance, and somewhat below the average height. His character (as revealed by his writings), his will (which is undoubtedly genuine), fragments of his letters and the allusions of his unprejudiced contemporaries, was that of a high-minded, kind-hearted man, devoted to his family and his friends, kind to his slaves, fair to his enemies and rivals, grateful towards his benefactors. When Platonism ceased to dominate the world of Christian speculation, and the works of Aristotle began to be studied without fear and prejudice, the personality of Aristotle appeared to the Christian writers of the 13th century, as it had to the unprejudiced pagan writers of his own day, as calm, majestic, untroubled by passion, and undimmed by any great moral defects, "the master of those who know".