Senses of 'being able' (3): through justifying love
Thesis XIII. Third, in the same doctor's view, we are said in a much fuller and closer sense to be able to do what belongs to true devotion through the love by which a person is justified. That love is simply a good will, a good act of willing; while we lack it we cannot live rightly, and when we have it we are said to be able to.
The love that confers the power of doing good has various degrees and stages of growth, and the power is greater or lesser accordingly. Weak at first and not equal to every good work, it grows gradually until it gains enough strength to overcome every allurement, every threat and every torment.
Latin
XIII. Tertio, ex ejusdem Doctoris sententia, dicimur multo plenius propinquiusque per charitatem, per quam homo justificatur, posse quae pertinent ad veram pietatem. Idque quia charitas seu dilectio ista, non est aliud quam voluntas seu volitio bona; quae quamdiu deest nobis, impossibile est bene vivere, quum autem adest, posse dicimur. Charitas autem per quam datur bene operandi potestas, varios gradus & incrementa habet, secundum quae potestas illa vel major, vel minor est: & initio infirma existens, nec ad omnia bona opera sufficiens, paulatim crescit, donec eo usque virium adolescat, ut cuncta invitantia, cuncta minantia, cuncta cruciantia superentur.