From Chapter III., Herakleitos of Ephesos

83. Ethics of Herakleitos
The moral teaching of Herakleitos is summed up in the rule "Follow the common." The "common" upon which Herakleitos insists is, nevertheless, something very different from common sense, for which, indeed, he had the greatest possible contempt (fr. 111). It is, in fact, his strongest objection to "the many," that they live each in his own world (fr. 95), as if they had a private wisdom of their own (fr. 92); and public opinion is therefore just the opposite of "the common." The rule is really to be interpreted as a corollary of his anthropological and cosmological views. The first requirement is that we keep our souls dry, and thus assimilate them to the one Wisdom, which is fire. That is what is really "common," and the greatest fault is to act like men asleep (fr. 94), that is, by letting our souls grow moist, to cut ourselves off from the fire in the world.

Herakleitos prepared the way for the Stoic world-state by comparing "the common" to the laws of a city. And these are even more than a type of the divine law: they are imperfect embodiments of it. They cannot, however, exhaust it altogether; for in all human affairs there is an element of relativity (fr. 91). "Man is a baby compared to God" (fr. 97). Such as they are, however, the city must fight for them as for its walls; and, if it has the good fortune to possess a citizen with a dry soul, he is worth ten thousand (fr. 113); for in him alone is "the common" embodied.