Letters 90.21

Posidonius then passes on to the farmer. With no less eloquence he describes the ground which is broken up and crossed again by the plough, so that the earth, thus loosened, may allow freer play to the roots; then the seed is sown, and the weeds plucked out by hand, lest any chance growth or wild plant spring up and spoil the crop. This trade also, he declares, is the creation of the wise,—just as if cultivators of the soil were not even at the present day discovering countless new methods of increasing the soil’s fertility!

Seneca, Letters to Lucilius 90.21, translated by Richard Mott Gummere