Cap. 6 Arg. 6: Prosper—many hear; wills prepared or not; mercy and judgment in the wills
Prosper brings the difference between believers and unbelievers back to the same point (Ad excerpta Genuensium, reply to Doubt 4): "Many hear the word of truth, but some believe and others contradict—so these will to believe, and those will not. Who does not know that? Who denies it? Yet when the Lord prepares the will for some and does not prepare it for others, we must ask what comes of mercy and what of judgment." And a little later: "Mercy and judgment have been done in the wills themselves."
Latin
Huc revocat Prosper discrimen credentium & non-credentium, Ad excerpta Genuens. resp. ad Dub. 4. Multi audiunt verbum veritatis, sed alii credunt, alii contradicunt: volunt ergo isti credere, nolunt illi. Quis hoc ignoret? quis hoc neget? Sed cum aliis praeparetur, aliis non praeparetur voluntas a Domino, discutiendum est utique quod veniat de misericordia, quod de judicio. Et paulo post, Misericordia & judicium in ipsis voluntatibus facta sunt.