Postponing further reference to this theory until the great name of Lucretius, its Roman exponent, is reached, we find a genuine scientific method making its first start in the person of Aristotle. This remarkable man, the founder of the experimental school, and the Father of Natural History, was born 384 B. C. at Stagira in Macedonia. In his eighteenth year he left his native place for Athens, where he became a pupil of Plato. Disappointed, as it is thought, at not succeeding his master in the Academy, he removed to Mytilene in the island of Lesbos, where he received an invitation from Philip of Macedon to become tutor to his son, the famous Alexander the Great. When Alexander went on his expedition to Asia, Aristotle returned to Athens, teaching in the "school" which his genius raised to the first rank. There he wrote the greater part of his works, the completion of some of which was stopped by his death at Chalcis in 322. The range of his studies was boundless, but in this brief notice we must limit our survey--and the more so because Aristotle's speculations outside natural history abound in errors--to his pioneer work in organic evolution. Here, in the one possible method of reaching the truth, theory follows observation. Stagira lay on the Strymonic gulf, and a boyhood spent by the seashore gave Aristotle ample opportunity for noting the variations, and withal gradations, between marine plants and animals, among which last-named it should be noted as proof of his insight that he was keen enough to include sponges. Here was laid the foundation of a classification of life-forms on which all corresponding attempts were based. Then, he saw, as none other before him had seen, and as none after him saw for centuries, the force of heredity, that still unsolved problem of biology. Speaking broadly of his teaching, the details of which would fill pages, its main features are (1) His insistence on observation. In his History of Animals he says "we must not accept a general principle from logic only, but must prove its application to each fact. For it is in facts that we must seek general principles, and these must always accord with facts. Experience furnishes the particular facts from which induction is the pathway to general laws." (2) His rejection of chance and assertion of law, not, following a common error, of law personified as cause, but as the term by which we express the fact that certain phenomena always occur in a certain order. In his Physics Aristotle says that "Jupiter rains not that corn may be increased, but from necessity. Similarly, if some one's corn is destroyed by rain, it does not rain for this purpose, but as an accidental circumstance. It does not appear to be from fortune or chance that it frequently rains in winter, but from necessity." (3) On the question of the origin of life-forms he was nearest of all to its modern solution, setting forth the necessity "that