Chapter 6: Ad 1 – 2 — generation; universal corruption
But he opposes those questions about original corruption to ours in vain: for they are not equal, nor have they any proving force at all. I answer the first: Why did Adam's moral corruption rather infect posterity than posterity's corruption stain Adam? Because moral corruption is propagated in no other way than by carnal generation: and posterity are begotten from Adam, but Adam is not begotten from them. To the second: Why did Adam's sin necessarily descend into posterity, and that of other fathers not so? Because Adam's sin was a change of the last end, and so brought a universal corruption into Adam's nature: but the unclean could not but beget the unclean, flesh not but flesh. Now the sins of other fathers could not be causes of this kind of corruption, since it was already produced in them, but effects by which it exercised and preserved itself. Therefore although we have drawn it most nearly from our nearest parents, yet it ought to be ascribed to Adam as its first author and spring.
Latin
Frustra autem istas de corruptione originali quaestiones nostris opponit: non enim sunt pares, nec ullam prorsus probandi vim habent. Respondeo ad primam, Cur Adami corruptio moralis posteros potius infecit, quam corruptio posterorum inquinavit Adamum? quia corruptio moralis non aliter quam per generationem carnalem propagatur: sunt autem posteri Adamaeo geniti, non autem Adamus ab illis. Ad 2. Cur Adami peccatum in posteros necessario descendit, caeterorum patrum non ita descendit? quia peccatum Adami fuit mutatio finis ultimi, atque adeo universalem in Adami naturam corruptionem induxit: immundus autem non potuit non immundum, caro non carnem gignere. Peccata vero aliorum patrum, hujusmodi corruptionis causae esse non poterunt, cum jam esset in eis producta, sed effecta quibus ipsa sese exercuit, & conservavit. Itaque quamvis a proximis parentibus eam proxime traxerimus, tamen Adamo, ut illius primo autori & scaturigini ascribi debet.