631. There is a difference of approach among theologians to the first part of the double nature of imputation, that concerning man's salvation, that is, the imputation of Christ's merit at discretion, and so the imputation of salvation. Some teach that the imputation is absolute as the result of the free exercise of power, and happens to those whose external or internal form is pleasing to God. The other opinion is that imputation occurs by foreknowledge in the case of those into whom grace is poured, so that that faith can be applied to them. Yet those two opinions are both aiming at one mark. They are like two eyes both focussing on one stone, or two ears both intent upon one song. At first sight it looks as though they are going in opposite directions, but they come together at the end and co-operate. For when both schools of thought proclaim man's complete impotence in spiritual matters, and any contribution on man's part is ruled out, it follows that that grace which allows the reception of faith when it is poured in, whether at discretion or from foreknowledge, is the result of a similar process of choice. For if that grace, which is called prevenient, were available to all, there would have to be an additional effort by some power of his own on man's part; and this is shunned like leprosy.