Jansenius: freedom saved in the divided sense (book 8, chapter 4)
Thesis XLIII. On the same reasoning as the Thomists, that bishop and those who hold to his teaching maintain that the efficacy of Christ's grace just described can be reconciled with the freedom of human choice in this state. The grace of Christ that determines the will to act in no way removes its power to act otherwise, even though it infallibly causes it to act. An agent should be judged free if it acts in such a way that it has the power not to act or to act otherwise. Freedom does not require that the will's not acting be compatible, at the same moment, with everything needed for action being present; it requires only that the will be able not to act.
So on their assumptions, once the motion of divine grace is given, the soul must indeed follow it in the composite sense; the will cannot resist God as he moves it, or dissent from what God wills to accomplish through it, and in that respect the force of divine grace is rightly called indeclinable and insuperable. In the divided sense, however, it is true that the will, even while grace moves it, can resist God, dissent from grace and turn aside elsewhere than God is leading it. For in consenting to grace it does not thereby lose the power to dissent; in yielding to God's motion it does not lose the power to resist; and in following God's lead it does not lose the power to turn aside where concupiscence draws it.
This is set out in Jansenius, De gratia Christi Salvatoris, book 8, chapter 4: 'As in the composite sense those expressions are true which say that the will, acted on by divine grace, cannot resist God, cannot dissent from what God wills to accomplish through it, cannot turn aside, cannot overcome; so, conversely, in the divided sense those are true which say that it can turn aside, can dissent, can overcome.'
Latin
XLIII. Eadem quoque cum Thomistis ratione, Episcopus iste, & qui doctrinae illius adhaerent, jam descriptam gratiae Christi efficaciam, cum Arbitrii humani, in hoc statu, libertate conciliari posse docent. Nimirum quia illa Christi gratia quae voluntatem ad agendum determinat, ab ea minime tollit potestatem aliter agendi, etiamsi infallibiliter efficiat ut agat. Agens autem illud liberum censeri debet, quod sic agit, ut habeat potestatem non agendi, aut aliter agendi. Neque ad libertatem necesse est, ut cum omnibus ad agendum requisitis stet simul ut non agat voluntas; sed solum ut possit non agere. Itaque, secundum illorum hypotheses, posita gratiae divinae motione, necesse est quidem in sensu composito animum illam sequi, nec potest voluntas Deo moventi resistere, & dissentire ab eo quod per eam vult operari Deus; adeoque vis divinae gratiae eo respectu recte dicitur indeclinabilis & insuperabilis: sed tamen in sensu diviso verum est, voluntatem, etiam quum gratia illam movet, posse Deo resistere, gratiae dissentire; & alio quam quo Deus illam ducit declinare: quia dum gratiae consentit, non propterea amittit potentiam dissentiendi, & dum Deo moventi cedit, potentiam resistendi, ac dum sequitur Dei ductum, potentiam divertendi quo trahit concupiscentia. Ut videre est apud Jansenium de gratia Christi salvatoris lib. 8. cap. 4. Sicut ergo, inquit, in sensu composito verae sunt ejusmodi Phrases, quibus voluntas acta per divinam gratiam, dicitur non posse resistere Deo, non posse dissentire ab eo quod per eam vult operari Deus, non posse declinare, non posse superare: ita e contrario in sensu diviso verae sunt, quibus dicitur posse declinare, posse dissentire, posse superare.