A notable point about this Greek philosophy is that the priest or the enchanter has nothing to say to it. The sage was a layman, who need fear no pope, no ban of the Church, in using his reason freely upon the problems even of theology. There were indeed isolated cases, where a man who denied the existence of the traditional gods, or was supposed so to do, was pursued by popular indignation. Diagoras of Melos, called the atheist, was driven from the societies which thought such teaching dangerous; Socrates was prosecuted in like manner, because he was suspected of spreading scepticism among the youth, but he was executed only because he behaved in a manner highly contumacious to the established order of the State. Had he defended himself in the ordinary routine, he would at most have been subjected to a fine. These isolated cases are only mentioned lest you should imagine that they were typical. Greek philosophy being secular, was therefore free. The earliest thinkers, those of the Ionic school, set themselves to solve by speculation the very question which now engrosses our deepest researches in physics. They thought out, or they inferred from their observations, that “things are not as they seem”; they found out, what we have attained by long experiment, that the many qualities our senses perceive are not fundamental or primary, that as Descartes and Locke and Spinoza taught, mechanical composition and varying degrees of motion in minute particles of the same kind may produce wholly diverse impressions. The most obvious and striking of these to the ordinary man is the case of colour. Descartes had anticipated that the pace of the rotation of particles made the differences; we know now that it is not rotation, but vibration of ether, and so with variation in tones. But the differences both of colours and sounds are due to the more or less rapid motion of the vibration. This was what Thales and Anaximenes and Anaximander felt when they said that the world consisted of one element, that moisture, caloric, ether, were the primitive stuff of which the world was composed. And these famous men were not mere metaphysicians, they showed their intellectual greatness in various ways. Thales actually predicted an eclipse, to the astonishment of his contemporaries.[45] He showed them that the lesser bear, ending in the pole star, was a better indication for the sailor to use than the greater. He solved the problem of measuring the height of an inaccessible object by comparing its shadow with that of a small one within reach. He gave valuable advices in politics. So that his metaphysic was both the source and the climax of a wide mental activity. So with Anaximander. He attempted the first map of the known world and made signal advances in astronomy. Anaximenes declared that eclipses were the concealing of one heavenly body by the interposition of another. These were great feats; but they were nothing in comparison to