The Athenians appointed him ambassador to Philip, king of Macedonia, father of Alexander the Great. Aristotle, having spent some time in Macedonia in settling the affairs of the Athenians, found, upon his return, that Xenocrates had been chosen master of the academy. Seeing that place thus filled he said, "It would be a shame for me to be silent, when Xenocrates speaks." He accordingly established a new sect, and taught doctrines different from those of his master Plato.
The celebrity of Aristotle, who now surpassed all his contemporaries in every kind of science, especially in the departments of philosophy and politics, induced Philip, king of Macedonia, to offer him the care of the education of his son Alexander, then fourteen years of age. Aristotle accepted. He continued Alexander's preceptor for eight years; and according to the testimony of Plutarch, taught him some secret doctrines which he communicated to none other.
The study of philosophy did not render the manners of Aristotle austere. He applied to business, and took an interest in everything that passed at the court of Macedonia. From respect to this philosopher, Philip rebuilt Stagira, his native city, which had been destroyed during the wars, and restored to their possessions all the inhabitants, of whom some had fled and others had been reduced to slavery.
When Alexander's education was finished, Aristotle returned to Athens, where he was well received on account of the mildness with which, for his sake, that city had been treated by Philip. He fixed upon a place in the Lyceum highly beautified with avenues of trees, where he established his school. He used to walk about when teaching and from this circumstance his sect was called _Peripatetic_. The Lyceum was soon thronged by a concourse of students whom Aristotle's reputation had drawn together from every quarter of Greece.
Alexander recommended to him to attend particularly to experiments in physical science. To facilitate his observations he sent him, besides 800 talents to defray expenses, a great number of huntsmen and fishermen to supply him from every quarter with subjects for experiment.
At that time Aristotle published his books of physics and metaphysics. Of this, Alexander who was now in Asia, got information. That ambitious prince, desirous of being in everything the first man in the world, was dissatisfied that the learning of his master should become common.