THE IONIAN SCHOOL: THALES.--The Ionian School is the most ancient school of philosophy known. It dates back to the seventh century before Christ. Thales of Miletus, a natural philosopher and astronomer, as we should describe him, believed matter--namely, that of which all things and all beings are made--to be in perpetual transformation, and that these transformations are produced by powerful beings attached to every portion of matter. These powerful beings were gods. Everything, therefore, was full of gods. His philosophy was a mythology. He also thought that the essential element of matter was water, and that it was water, under the influence of the gods, which transformed itself into earth, air, and fire, whilst from water, earth, air, and fire came everything that is in nature. ANAXIMANDER; HERACLITUS.--Anaximander of Miletus, an astronomer also, and a geographer, believed that the principle of all things is _indeterminate_--a kind of chaos wherein nothing has form or shape; that from chaos come things and beings, and that they return thither in order to emerge again. One of his particular theories was that fish were the most ancient of animals, and that all animals had issued from them through successive transformations. This theory was revived for a while about fifty years ago. Heraclitus of Ephesus (very obscure, and with this epithet attached permanently to his name) saw all things as a perpetual growth--in an indefinite state of becoming. Nothing is; all things grow and are destined to eternal growth. Behind them, nevertheless, there is an eternal master who does not change. It is our duty to resemble him as much as we can; that is to say, as much as an ape can resemble a man. Calmness is imperative: to be as motionless as transient beings can. The popular legend runs that Heraclitus "always wept"; what is known of him only tends to prove that he was grave, and did not favour emotionalism. ANAXAGORAS; EMPEDOCLES.--Anaxagoras of Clazomenae, above all else a natural philosopher, settled at Athens about 470 B.C.; was the master and friend of Pericles; was on the point of being put to death, as Socrates was later on, for the crime of indifference towards the religion of the Athenians, and had to take refuge at Lampsacus, where he died. Like Anaximander, he believed that everything emerged from something indeterminate and confused; but he added that what caused the emergence from that state was the organizing intelligence, the Mind, just as in man, it is the intelligence which draws thought from cerebral undulations, and forms a clear idea out of a confused idea. Anaxagoras exerted an almost incomparable influence over Greek philosophy of the classical times.