All learning is dangerous. Knowledge, we are told, is itself power; but while power is only greater or less, knowledge is right or wrong, whoever holds it and however little they hold. In the development of zoöology and botany, for example, broad-minded polymaths bowed over and over to narrow-minded travelers. Learning, like war, is subject to sudden reversals and improbable victories. Empires of learning have fallen: Scholastic theology, Marxist philosophastery; and the territories of learning are subject to epochal overrunings from without: Descartes, Darwin, Marx.
Tyrants always first burn the books and bury the scholars. They have never got them all; but what the survivors have learned, whether alone with the hidden or forbidden books in their attics, or reciting them over and over to keep them straight in the attics of their brains; what they have learned while despised as wizards, devil-traffickers, heretics, sentimentalists, reactionaries, pedants, or just madmen—is that an age is not made dark or light by its luminaries, but by the lesser lights crowding around and beside them.
In an age of darkness an incandescent mind at best disorients, at worst horrifies those who have been accustomed to live in darkness. Great lights are bearable only to those with eyes adjusted to light, to those routinely aware, in themselves and in those around them, of the possibility, of the reality, and of the worth of light. Those who have walked in darkness all their lives, who have given their whole trust and faith to one or another memorized set of directions that have saved them from most falls and collisions without requiring them to be aware of where they are—will hate light. They have been blind to the world, and worse, unmirrored, unknown to themselves. Light will burn them, and they will hide from it, shroud it, or put it out with slogans and proverbs, with laughter and mockery and shouting down; with exiling potshards, with hemlock, with crosses, with the auto-de-fé and the pyre, with the breaking wheel, with guns, with imprisonment, with transportation, with impoverishing lawsuits.
Greatness requires audient mediocrity not for contrast, but for support. The opposition the great meet from the mediocre is but the resistance of the water to the swimmer. What holds them back also holds them up.