1. This is indeed a most intricate subject, but if you pray to him who said: 'It is not you who speak, but the Spirit of your Father who speaks in you' (Matthew 10:20); and elsewhere, 'Open wide your mouth, and I will fill it' (Psalm 81:10): those things which to me as a man are impossible, become possible when the Lord enlightens or teaches. Let us therefore consider what causes go before, and what vices follow. And that this may seem more credible, let not your prudence seek this out from me; but let divine Scripture, when consulted, answer you, and me, and all: which, as if we were now inquiring of it, has set forth an unalterable verdict, saying: 'Pride is the beginning of all sin' (Sirach 10:13).
What can be said more plainly, what more credibly? 'The beginning,' it says, not of some sin, but 'of all sin is pride': so that it might evidently show that pride itself is the cause of all sins; since pride is not only itself a sin, but also no sin could be, can be, or will be able to be committed without it. For indeed every sin is nothing else than a contempt of God, by which his precepts are trampled underfoot. And nothing else persuades men to this contempt of God except pride; which even in the devil himself, so that the devil might be made from an angel, was the cause of eternal ruin (Isaiah 14:13; Luke 10:18). And so he too, knowing that he had fallen from the heavens through pride and had been thrust into this prison of the murky air;
to overthrow the man whom God had made without any sin, he persuaded by serpentine cunning the vice of pride (Genesis 3:14), being certain that, once pride — which is the cause of all evils — was received, he would now easily perpetrate all sins, which are conceived only by a proud mind. 2. Hence it is that this same first man, corrupted by the exaltation of the proud spirit, consigned all his posterity, which was radically in him, to the necessity of corruption and mortality: so that, made corruptible and mortal, he should beget creatures corruptible and mortal; and thus what punishable pride had done in him became in all born of him the penalty of sin.
And therefore we can no longer resist sin in the way he could, for whom not to sin was nothing other than not to will it. But for us, willing to live blamelessly is not enough, unless divine power assists this very will of ours, which fails through feeble ability. For while still-sound nature could help him toward not sinning, vitiated nature now hinders us; and the will to sin alone made him sin, whereas the already-incurred necessity of sin for the most part even compels us. For which reason we cry out to God and say: 'Deliver me from my necessities' (Psalm 25:17). And so perhaps for this reason divine Scripture says, 'Pride is the beginning of all sin' (Sirach 10:13);
because it went before in the devil, and through it man was overthrown, concerning whom the Apostle says: 'By one man sin entered into the world, and by sin death; and so it passed upon all men, in whom all have sinned' (Romans 5:12). 3. But as for us, who sinned when the first man sinned — not in our own separate life, but in his nature, in which we existed — we contracted corruption as it were from the root of pride corrupted by disease, and in this very corruption of ours we have all the causes of sins: we who are not made corruptible because we sin; but because we are corruptible, we commit every sin out of this very corruption of ours.
But the first man did not sin because he was corruptible; rather, while he was incorrupt, he corrupted himself by sinning, and transmitted his corruption to us by propagation; and therefore there — where we shall be without any sin — all mortality and all corruption that came from sin must be taken away from us; but here, where our nature, weakened by fault, is not yet healed but is still being healed through grace, that vicious concupiscence resists our pious efforts — concupiscence that is not natural, but implanted and inserted penally into our nature: which was made by sin, and, if it conquers, makes sin. Though, as long as we live mortally, we have it,
yet let us not aid it by the zeal of our will, and we conquer it: since we sin not by feeling it in us, but by consenting to it; nor does it conquer us the instant it has assailed us, but only if it has cast down our mind (which God forbid) from the loftiness of its resolve into consent to sin.