text: But Posidonius again remarks: "Democritus is said to have discovered the arch, whose effect was that the curving line of stones, which gradually lean toward each other, is bound together by the keystone." I am inclined to pronounce this statement false. For there must have been, before Democritus, bridges and gateways in which the curvature did not begin until about the top. 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.