Xenophanes of Colophon, one of the twelve Ionian cities of Asia Minor, deserves, however, a passing reference. He, with Parmenides and Zeno, are the chief representatives of the Eleatic school, so named from the city in southwestern Italy where a Greek colony had settled. The tendency of that school was toward metaphysical theories. He was the first known observer to detect the value of fossils as evidences of the action of water, but his chief claim to notice rests on the fact that, passing beyond the purely physical speculations of the Ionian school, he denied the idea of a primary substance, and theorized about the nature and actions of superhuman beings. Living at a time when there was a revival of old and gross superstitions to which the vulgar had recourse when fears of invasions arose, he dared to attack the old and persistent ideas about the gods, as in the following sentences from the fragments of his writings: "Homer and Hesiod have ascribed to the gods all things that are a shame and a disgrace among men, theft and adulteries and deception of one another." "There never was nor will be a man who has clear certainty as to what I say about the gods and about all things; for even if he does chance to say what is right, yet he himself does not know that it is so. But all are free to guess." "Mortals think that the gods were born as they are, and have senses and a voice and body like their own. So the Ethiopians make their gods black and snub-nosed; the Thracians give theirs red hair and blue eyes." "There is one god, the greatest among gods and men, unlike mortals both in mind and body." Had such heresies been spoken in Athens, where the effects of a religious revival were still in force, the "secular arm" of the archons would probably have made short work of Xenophanes. But in Elea, or in whatever other colony he may have lived, "the gods were left to take care of themselves." Greater than the philosophers yet named is Heraclitus of Ephesus, nicknamed "the dark," from the obscurity of his style. His original writings have shared the fate of most documents of antiquity, and exist, like many of these, only in fragments preserved in the works of other authors. Many of his aphorisms are indeed dark sayings, but those that yield their meaning are full of truth and suggestiveness. As for example: "The eyes are more exact witnesses than the ears." "You will not find out the boundaries of soul by travelling in any direction." "Man is kindled and put out like a light in the nighttime." "Man's character is his fate." But these have special value as keys to his philosophy: "You cannot step twice into the same rivers; for fresh waters are ever flowing in upon you." "Homer was wrong in saying: 'Would that strife might perish from among gods and men!' He did not see that he was praying for the destruction of the universe; for, if his prayer were heard, all things would pass away."