706 ARISTOTLE IT years of age went to pursue his studies m Athens, where he resided for 20 years. He was a pupil of Plato, whom he sincerely admired, though opposed to him in philosophy. Plato was accustomed to call him, on account of his enthusiasm for knowledge and his restless in- dustry, the " intellect of his school." About 343 B. C. Philip of Macedon made him the teacher of his son Alexander, at that time 13 years old. His influence on Alexander and Philip was for many years very great and salutary, and Philip rebuilt at his request the city of Stagira, which had been destroyed, and erected there, in a pleasant grove, a school called Nymphseum, where Aristotle was to teach. Alexander after the conquest of the Persian kingdom presented him with 800 talents, or nearly a million of dollars. He also sent to him whatever he discovered on his marches that was unknown in Greece, such as plants and animals for scientific examination, and is said to have been accompanied by him in several of his expeditions. Aristotle re- turned to Athens in 335, or, according to Am- monius, in 331, bringing with him his scientific collections, and established a new school of philosophy in the Lyceum, a gymnasium near the city. In the forenoon he instructed his intimate pupils in a philosophical way, which lectures were called esoteric ; and in the even- ing he taught a large popular circle about plainer matters, in what were called exoteric or public lectures. His philosophical school is called the Peripatetic, because he taught while walking up and down (irfpnraTuv), or from the shady walks (irepiiraroi) around the Lyceum in which he delivered his lectures, and which in the time of Plutarch were still pointed out to the traveller. His friendly relations with Alexander were at length interrupted, perhaps on account of admonitions which he sent to that conqueror when, in his later years, he precipitated himself into a dissolute life. Yet the Athenians suspected him of partisanship for Macedonia, accused him of impiety, and forced him to flee to Chalcis, where he died. Only a part of his numerous writings on almost every branch of science and art were then published ; of the remainder many were lost, and many published only in the first centuries of the Christian era. The most important of them bear the following titles : " Organon " or "Logic," "Rhetoric," "Poetics," "Ethics," " Politics," " History of Animals," " Physics," " Metaphysics," " Psychology," and " Meteor- ology." His writings on mathematics, economy, and history are lost^ as well as his letters, and a work called Politiai, which contained 158 ancient state constitutions and legislations. Many books bearing his name are spurious, and it is only in the present century that the spurious begin to be sifted from the genuine. His style is difficult to understand, not only because of the intricacy of the subjects, but also on account of the technical terms entirely his own. No other philosopher has exerted so large an influence on so many centuries, and on the ideas of so many nations, as Aristotle. His merits as a metaphysical think- er may perhaps be variously estimated, but his performances in natural science, which he first created, and his method of philosophy, constitute his greatness. He was the first care- ful observer, dissector, and describer of ani- mals. He first divided the animal kingdom into classes ; described a great many animals before unknown to the scientific world ; came near discovering the circulation of the blood ; discriminated between the several faculties, the nourishing, feeling, concupiscent, moving, and reasoning powers of animal organism, and attempted to explain the origin of these powers within the body; and built his moral and political philosophy on the peculiarities of human organization. His philosophical method consists in the principle that all our thinking must be founded on the observation of facts. Logic is the fundamental science, and the principles which he laid down for it have never been superseded. It is ac- knowledged by Kant and Hegel, the two most profound thinkers of Germany, that from the time of Aristotle to their own age logic had made no progress. He invented the categories, or fundamental forms of thought, universal ex- pressions for the ever-changing relations of things, and limited their number to ten ; and he devised the so-called " syllogistics," or science of forming correct conclusions. He likewise became the father of modern psychology, show- ing how the mind creates its speculative meth- ods and general notions ; and that though we cannot prove their correspondence with the reality, because there is no direct proof for things which transcend our senses and obser- vation, yet we are always compelled to recur to these general notions and take them for in- dispensable forms of thinking, if we will think at all. Every science must, according to Aris- totle, have a fundamental principle, which need not and cannot be logically proved, because it is in itself certain, and accepted as manifest truth. Aristotle first discriminated between the substance of things and their accidental peculiarities, and created the philosophical no- tions of "matter" and of "form." He also established the philosophical notions of " space " and "time," and showed their connection with matter, while he first furnished the world with what is commonly called the cosmological ar- gument for the existence of God. He states it thus : Although every single movement and ex- istence in the world has a finite cause, and every such finite cause another finite cause back of it, yet back of this infinite series of finite causes there must be an infinite immaterial being, a first something, unmoved, all-moving, pure energy, absolute reason, God. In psychology and anthropology, Aristotle is the author of the theory of different powers of the soul, of dis- tinct feeling, willing, reasoning, and moving powers or faculties. The reasoning power is
