(Student Guide to World Philosophy)

Ancient tradition has termed Heraclitus “obscure,” although many of the passages in his fragmentary Peri physeos (on nature), which consists of fewer than 150 sentences, are very clear in their intent and content—for instance, the denunciation of his fellow citizens:The Ephesians ought to hang themselves, every one who is of age, and leave the city to the boys. They who threw out Hermodorus, the worthiest man of them, saying: “Let no one of us be the worthiest, but if there is one, let him go somewhere else, among others.”

or his compliments to his eminent predecessor:Learning many things does not teach one to have intelligence; else it would have taught Hesiod and Pythagoras, also Xenophanes and Hecataeus.

or his estimate of pious individuals:They “purify” themselves by staining themselves with different blood, as if one who stepped into mud should wash it off with mud. However, one would be thought mad, if any man should see him behaving this way. And they pray to these idols, just as if one were to have a conversation with a house—knowing naught of the nature of gods and heroes.

or such remarks about human imbecility as “Dogs bark at every one they do not know” and “Donkeys would choose garbage rather than gold.” Besides Hermodorus, only Bias of Priene escaped Heraclitus’s contempt, and that was because Bias had said, “Most men are bad.”