Seneca, Ep. Mor., 38.2.
[Verba sermonis] seminis modo spargenda sunt, quod quamvis sit exiguum, cum occupavit idoneum locum, vires suas explicat et ex minimo in maxima auctus diffunditur. Idem facit ratio: non late patet, si aspicias; in opere crescit.
[The words of conversation] should be scattered like seeds, which, though small, when they find a suitable location, unfold their strength and spread from the smallest to the greatest size. Reason works in the same way: it seems no great thing to the eye, but grows in its working.
Ev. Mark (Vulg.), 4.30-32.
Et dicebat, “Cui adsimilabimus regnum Dei? Aut cui parabolae conparabimus illud? Sicut granum sinapis, quod cum seminaturm fuerit in terra, minus est omnibus seminibus quae sunt in terra, et cum seminarium fuerit, ascendit et fit maius omnibus holeribus et facit ramos magnos, ita ut possint sub umbra eius aves caeli habitare.”
And he said, Whereunto shall we liken the kingdom of God? or with what comparison shall we compare it? It is like a grain of mustard seed, which, when it is sown in the earth, is less than all the seeds that be in the earth: but when it is sown, it groweth up, and becometh greater than all herbs, and shooteth out great branches; so that the fowls of the air may lodge under the shadow of it.