were she to fall into the hands of the Persians, married her, and she accompanied him in his flight. She made him an excellent wife, and Aristoteles had always a fervent and sincere affection for the patriotic and philosophical prince his friend. After two years’ residence in Mitylene, Aristoteles was invited by Philip to return to Macedonia, to superintend the education of his son Alexander, the future Alexander the Great, then fourteen years old. He was with this very able prince during about four years, and instructed him in morality, politics, and natural history. It was a strange position for a student of nature to occupy, and that he did his duty to his pupil is evident. It is the universal opinion that much that was admirable in the character of Alexander the Great was due to the influence of Aristoteles. The great conqueror was fond of literature, delighted in physical and even medical pursuits, sought the intimacy of men who thought, rather than that of men who had no other recommendation than titles and riches, and was devoted to the study of nature. These were the fruits of Aristoteles’ instruction, and it must be remembered that Alexander differed entirely in his conduct from the brutal conquerors who have been, over and over again, the scourge and curse of mankind. Aristoteles lost his wife during this time, and she left him an only daughter. Then Philip was assassinated, and his son reigned at Macedon for two years, and then began his great expedition into Asia. Aristoteles accompanied his pupil to Athens, and parted with him never to see him again, but still to influence him for years. Unfortunately, however, Aristoteles recommended a relation, named Callisthenes, to the young king, and it was the cause of a rupture of friendship in years to come. Left to himself, our hero resolved to open a school for the benefit of the Athenian youth, and to teach good learning in philosophy and nature. He chose a house near a temple of Apollo Lyceius, which was called the “Lyceum,” and attached to it was a garden with walks, where the instruction was given. The Greek word for the walks was _peripatua_, and the school was called that of the peripatetics. His habit was to give one lecture in the early part of the day, on the more difficult parts of his teaching, to his more advanced students; and this was called the morning walk, and lasted till the hour when people dressed and anointed themselves. Another lecture, called the evening walk, was on more popular subjects, and to a larger and less select class. It was during these thirteen years of teaching that Aristoteles composed and completed the greater part of his works which have descended to our days. Amongst them are treatises on natural history, the result of his own observations and of the carefully selected works of others.