Henry David Thoreau, an obscure 19th Century classicist and journalist who earned a reputation as a decent translator of Greek works, once reflected on the profound presence of Evil in the world:
Are there not two powers?
—Journal of Henry David Thoreau, Jan 9, 1853
Among the Greek classics which Thoreau is known to have read is Plutarch’s Moralia, which includes an essay
wherein Plutarch argues that the prevailing wisdom of all peoples is based upon a common belief in a cosmic dualism of Good and Evil.
… it is from two opposite Principles and two antagonistic Powers; … that Life becomes of a mixed nature; …
—Plutarch, On Isis and Osiris, XLV
The primary example provided by Plutarch for what he regards as a universal belief is the Zoroastrian religion, to which he dedicates two sections of “On Isis and Osiris”.
And this is the opinion of most men, and those the wisest, for they believe, some that there are Two Gods, as it were of opposite trades—one the creator of good, the other of bad things; others call the better one “God,” the other “Daemon,” as did Zoroaster the Magian, …
—Plutarch, On Isis and Osiris, XLVI
But when Plutarch endorses these cosmic dualisms, he endorses them as representations of a deep, moral-metaphysical reality.
Just before Plutarch brings up Zoroaster, he argues against Stoic Deism and the Materialism of Democritus and Epicurus, criticizing them as opposite, equally unacceptable extremes. He summons our friend Heraclitus to introduce the alternative:
… the harmony of the universe is reciprocal, like that of a lyre or bow, according to Heraclitus, …
—On Isis and Osiris, XLV
And just after discussing Zoroaster, Plutarch returns to Heraclitus, combining three of the Ephesian philosopher’s fragments into a single compound argument:
Heraclitus directly calls Mars, father, lord, and ruler of all things; and says that Homer, when he prays that “Perish Contention, both from gods and men,” forgets that he is cursing the origin of all things, inasmuch as they derive their origin from contention and antipathy, and the Sun will not overpass his appointed limits, otherwise: “The avenging tongue of Law would find him out,” …
—On Isis and Osiris, XLVIII
Thus we find in Plutarch Zoroaster sandwiched between slices of Heraclitus. One might dare suggest that Plutarch saw some correspondence between those two ancient thinkers, one an Iranian, perhaps a Mede or a Persian, and the other a Greek subject of the Persian Empire.
Seeing Zoroaster in this light, not as a literalist but as a proto-Heraclitean, I wonder what fruit an imaginary encounter between Nietzsche and Plutarch might bear. What if the German were to suggest to the Greek that he had seen the potential in Zarathustra and thereby reformed the Persian prophet, beyond Good and Evil, into a Heraclitean? Would Plutarch have been surprised? Might Plutarch have asserted that Zarathustra was a Heraclitean all along?