It is after a generation of such persistent questioning of Nature and custom by pioneer Greeks that we find in Herakleitos of Ephesus (fl. 500 B.C.)--still in the Ionian culture-sphere--a positive and unsparing criticism of the prevailing beliefs. No sage among the Ionians (who had already produced a series of powerful thinkers) left a deeper impression than he of massive force and piercing intensity: above all of the gnomic utterances of his age, his have the ring of character and the edge of personality; and the gossiping Diogenes, after setting out by calling him the most arrogant of men, concedes that the brevity and weight of his expression are not to be matched. It was due rather to this, probably, than to his metaphysic--though that has an arresting quality--that there grew up a school of Herakliteans calling themselves by his name. And though doubt attaches to some of his sayings, and even to his date, there can be small question that he was mordantly freethinking, though a man of royal descent. He has stern sayings about "bringing forth untrustworthy witnesses to confirm disputed points," and about eyes and ears being "bad witnesses for men, when their souls lack understanding." [510] "What can be seen, heard, and learned, this I prize," is one of his declarations; and he is credited with contemning book-learning as having failed to give wisdom to Hesiod, Pythagoras, Xenophanes, and Hekataios. [511] The belief in progress, he roundly insists, stops progress. [512] From his cryptic utterances it maybe gathered that he too was a pantheist; [513] and from his insistence on the immanence of strife in all things, [514] as from others of his sayings, that he was of the Stoic mood. It was doubtless in resentment of immoral religion that he said [515] Homer and Archilochos deserved flogging; as he is severe on the phallic worship of Dionysos, [516] on the absurdity of prayer to images, and on popular pietism in general. [517] One of his sayings, êthos anthrôpô daimôn, [518] "character is a man's dæmon," seems to be the definite assertion of rationalism in affairs as against the creed of special providences.