Senses of 'being able' (2): through faith
Thesis XII. Second, according to the same doctor, we are said, in a somewhat closer sense, to be able through faith to live rightly, withstand every temptation and avoid sins, even though we lack love for God, God's actual help and the will's inner strength.
Faith of itself cannot do any of this. But it is the seed of prayer, and by prayer we usually obtain love, helping grace and strength of will; that is why we are said to be able to do these things through faith itself.
Latin
XII. Secundo, juxta eundem Doctorem, paulo propinquius dicimur, posse bene vivere, omnibusque tentationibus resistere, & peccata cavere per fidem, quamvis dilectione Dei, & actuali Dei adjutorio, internisque viribus voluntatis careamus. Nam quamvis fides ista omnia per se nullo modo possit, quia tamen est semen orationis, per quam charitatem & gratiam adjuvantem & voluntatis vires impetrare solemus, hinc per ipsam fidem ista posse dicimur.