The testimony of Pareus
Thesis XXX. So that no one can falsely allege that Protestants think otherwise, or that we are pinning on them a doctrine not their own, we will cite a few of their statements on the matter as a sample. To go through them all would be endless labour, and needless; besides, the matter is plain enough to anyone who pays attention.
Pareus, then, writing on Bellarmine's De justificatione, book 4, chapter 10, says: 'The question is whether the justified can fulfil the divine law. Our opponent affirms it absolutely; we grant it of an imperfect, begun fulfilment and deny it of a perfect one.' Later, explaining what fulfilling the law means, he says: 'To fulfil God's law, speaking absolutely, is to give the divine law a perfect obedience without any defect, and I confess we teach that the justified cannot do this.'
He goes on to say that we teach fulfilling the law is impossible for a justified person, not outright, as Bellarmine falsely charges us, but with respect to the law's exactness (ἀκρίβεια), which rules out every defect. A person in the state of grace can therefore fulfil the law in a begun way, that is, begin the new obedience of the law according to all its precepts, but cannot fulfil it absolutely, without any sin.
Latin
XXX. Ac nequis calumnietur Protestantes diversum sentire, & nos alienam ipsis affingere doctrinam, hac de re quaedam eorum testimonia velut in specimen proferemus. Nam singula persequi infinitae operae, & superfluum esset. Et res alioqui est attendenti per se satis manifesta. Igitur Paraeus scribens in Bellar. lib. 4. de Justif. cap. 10. In quaestione, inquit, est, An justificati possint legem divinam implere, quod adversarius absolute affirmat, nos de impletione imperfecta, inchoata damus, de perfecta negamus. Et postea explicans quid sit legem implere, Legem Dei implere, inquit, si absolute loquaris, est legi divinae obedientiam perfectam, sine ullo defectu, praestare, quod justificatos non posse nos docere fateor. Quibus subjungit nos docere homini justificato legem implere impossibile esse, non plane, ut nobis falso imponit Bellarminus, sed quoad legis ἀκρίβειαν, quae omnem defectum excludit, adeoque hominem in statu gratiae posse legem implere inchoate, hoc est, novam obedientiam legis, secundum omnia ejus praecepta inchoare: non posse vero implere absolute sine omni peccato.