Letters 90.32

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.

Seneca, Letters to Lucilius 90.32, translated by Richard Mott Gummere