That a Man already in Mortal Sin cannot avoid more Mortal Sin without Grace*

WHEN it is said that it is in the power of free will to avoid putting obstacles to grace, that saying is to be understood of those in whom the natural faculty is unimpaired by sin.* But if the will has fallen into evil courses by some previous inordinate act, it will not be altogether in its power to avoid putting obstacles in the way of grace. For though for some momentary occasion it may abstain from some particular act of sin by its own power, nevertheless, if left long to itself, it will fall into sin; and by sin an obstacle is put to grace. For when the mind of man turns aside from the state of righteousness, it clearly puts itself out of relation with its due end. Thus what ought to be the prime object of its affections, as being its last end, comes to be less loved than that other object to which it has inordinately turned, making of it another last end. Whatever in such a posture of the mind occurs to fit in with the inordinate end, however inconsistent with the due end, will be chosen, unless the will be brought back to due order, so as to prefer the due end to all others, and that is an effect of grace. But the choice of anything inconsistent with the last end puts an obstacle in the way of grace, as grace goes to turn one in the direction of the end. Hence after sin a man cannot abstain from all further sin before by grace he is brought back to due order.

Moreover, when the mind is inclined to a thing, it is no longer impartial between two alternatives. And that to which the mind is more inclined it chooses, unless by a rational discussion, not unattended with trouble, it is withdrawn from taking that side: hence sudden emergencies afford the best sign of the inward bent of the mind. But it is impossible for the mind of man to be so continually watchful as rationally to discuss whatever it ought to do or not to do. Consequently the mind will at times choose that to which it is inclined by the present inclination: so, if the inclination be to sin, it will not stand long clear of sin, thereby putting an obstacle in the way of grace, unless it be brought back to the state of righteousness.

Further we must consider the assaults of passion, the allurements of sense, the endless occasions of evil-doing, the ready incitements of sin, sure to prevail, unless the will be withheld from them by a firm adherence to the last end, which is the work of grace.

Hence appears the folly of the Pelagian view, that a man in sin can go on avoiding further sins without grace. On the contrary the Lord bids us pray: Lead us not into temptation, but deliver us from evil.

But though persons in sin cannot of their own power help putting obstacles in the way of grace, unless they be forestalled by some aid of grace,* still this lack of power is imputable to them for a fault, because it is left behind in them by a fault going before; as a drunken man is not excused from murder, committed in drunkenness, when he gets drunk by fault of his own.* Besides, though this person in sin has it not in his unaided power altogether to avoid sin, still he has power here and now to avoid this or that sin: hence whatever he commits, he voluntarily commits, and the fault is imputed to him not undeservedly.*

3.160 : That it is reasonably reckoned a Man's own Fault if he be not converted to God, although he cannot be converted without Grace
3.162 : That some Men God delivers from Sin, and some He leaves in Sin