When, on the assassination of Philip, Alexander mounted the throne and embarked on that expedition which extended the sway of Macedon over half the known world, he showed his gratitude by making his instructor a munificent present equivalent to nearly $1,000,000, and employed two or three thousand men to fill his cabinets with specimens. Thus supplied with material and funds, Aristotle, established in Athens since 335 B.C. as a distinguished teacher despite his traditional lisp and insignificant appearance, vigorously prosecuted his scientific labors. At the Lyce’um, Apollo’s temple, he gave instruction to his disciples, walking up and down in the covered paths (_peripatoi_) about the building—whence the name of his school, _Peripatetic_. He mastered all existing knowledge, regarding learning as “an ornament to men in prosperity, a refuge in adversity;” and for thirteen years divided his time between his pupils and his literary work. The news of Alexander’s sudden death was the signal for Aristotle’s enemies, no longer restrained by fear of his royal friend, to show their hand. Impiety was alleged against him; but mindful of the fate of Socrates, and, as he said, to prevent the Athenians from sinning a second time against philosophy, he retired to Chalcis on the island of Eubœa, where he died within a year. PHILOSOPHY AND WRITING OF ARISTOTLE.—While to some extent following his master, from several of Plato’s doctrines Aristotle felt compelled to dissent; truth, he said, was dearer to him than any friend.[35] He did not accept the Ideal theory, but inclined to materialism or to pantheism, making _reason_ divine and omnipresent. He doubted his own immortality, holding that the soul could not exist apart from the body, and that there is “nothing good or bad beyond to the dead.” His style was dry, elliptical, and full of technicalities; if we compare it with Plato’s, we have the opposite poles of the magnet. Plato was all imagination, Aristotle was thoroughly practical. The inspiration of the one was a passionate love of wisdom; the forte of the other was power of analysis, a wonderful faculty of systemizing knowledge. The master captivated the heart; the pupil convinced the reason. “The philosophy of Plato,” says Dr. Draper, “is a gorgeous castle in the air; that of Aristotle is a solid structure laboriously founded on rock.” Aristotle’s style is devoid of ornament, and his subjects are too abstruse for the general run of readers; but he was a keen observer and a close reasoner. A few paragraphs from his Rhetoric, in which he analyzes the peculiarities of old age, will show how well he understood human nature. THE DISPOSITION OF THE OLD.