Letters 90.33

It seems to have quite slipped your memory that this same Democritus discovered how ivory could be softened, how, by boiling, a pebble could be transformed into an emerald,—the same process used even to-day for colouring stones which are found to be amenable to this treatment! It may have been a wise man who discovered all such things, but he did not discover them by virtue of being a wise man; for he does many things which we see done just as well, or even more skilfully and dexterously, by men who are utterly lacking in sagacity.

Seneca, Letters to Lucilius 90.33, translated by Richard Mott Gummere