Second reason: what a rational creature needs to reach its natural end, knowing and loving God, is natural
Further, what an uncorrupted rational creature needs in order to reach its natural end is natural to it. The end of a rational creature is to know, love and worship God, for that is what God made it for.
It cannot reach that end if it is created without righteousness and holiness, that is, if it is thought of as stripped of the gifts we lost through Adam's sin.
Latin
LIII. Praeterea creaturae rationali non corruptae naturale est id sine quo naturalem suum finem assequi nequit. Sed finis creaturae rationalis est, ut Deum agnoscat, amet atque colat. Ad hoc fuit enim a Deo condita. Hunc finem autem assequi non potest, si absque justitia & sanctitate creetur; Et si consideretur ut destituta donis illis quae per Adami peccatum amisimus.