Jansenius: no merit before the first good will; cooperating grace and growth
Thesis LV. Operating grace, then, as he carefully observes, alone produces the first good will in a person. This is not because the person does not at the same time contribute his own influence to that will, that is, to the will's movement and consent, but because grace works that movement while we contribute nothing toward having it, whether by asking, desiring, striving or meditating, and so bring no good merit whatever with respect to that will.
Such merit is impossible, he says, for the very reason that this is laid down to be the first good will, to which one turns from a bad will.
Cooperating grace, in turn, is so called because it works something in us not alone but with us cooperating at the same time. It does so not merely by a simultaneous influence, by which we cooperate with operating grace too, but ahead of that grace's effect, by willing, believing, desiring, asking, knocking, taking pains and so even meriting.
Thus the effect of cooperating grace is the whole growth of that first good will, up to the height of human perfection (On the Grace of Christ the Saviour, book 4, chapter 15).
Latin
LV. Gratia operans igitur, ut diligenter observat, sola primam bonam voluntatem in homine efficit, non quod homo non simul in illam voluntatem, hoc est, in voluntatis motum atque consensionem influat, sed quia motum illum gratia operatur, nobis nihil ad eum habendum conferentibus, petendo, desiderando, studendo, meditando, atque ita nihil omnino boni meriti, respectu illius voluntatis, afferendo. Illud enim impossibile esse, hoc ipso quo statuitur, esse prima voluntas bona, ad quam ex mala convertitur. Vicissim vero gratia cooperans sic dicta est, quia operatur aliquid in nobis non sola, sed nobis simul cooperantibus; non per simultaneum tantum influxum, quo etiam cooperamur gratiae operanti, sed praevie ad effectum istius gratiae, Volendo, credendo, desiderando, petendo, pulsando, satagendo, adeoque etiam promerendo; ita ut ejus gratiae cooperantis effectus sit universum primae voluntatis illius bonae incrementum, usque ad apicem perfectionis humanae. De gratia Christi salvatoris lib. 4. cap. 15.