Efficacy as congruity of the call with free choice
Thesis CXXV. On their view, then, 'the efficacy of grace consists in a certain congruity and attunement of the divine call with free choice; given this, the effect follows infallibly, in accordance with God's foreknowledge.' These are Peter of Saint Joseph's words in his Idea of speculative theology, book 4, chapter 7, resolution 7.
In the treatise on divine grace he notes that this congruity is not to be drawn merely from place or time, as though grace were efficacious just because it comes at a fitting place and time. Congruous and efficacious grace is certainly given only at a fitting time. Still, its congruity and efficacy are not mainly derived from the time; something must be found in the call itself that makes it take effect at that time and place, since a different call, though sufficient, would achieve nothing at that very moment. In his sense, therefore, 'that congruity of grace is simply a certain proportion and fit between grace itself and the will in such a state that the act follows infallibly' (disputation 7, section 9, number 66).
Latin
CXXV. Itaque juxta illos, Efficacia gratiae consistit in certa congruitate, & contemperatione vocationis divinae cum libero arbitrio, qua posita, juxta praescientiam Dei sequitur infallibiliter effectus. Quae sunt verba Petri a Sancto Joseph capite septimo libri quarti, in Idea Theologiae speculativae, Resolutione 7. In tractatu vero de divina gratia observat congruitatem illam non esse sumendam simpliciter a loco, vel tempore; quasi gratia ideo sit efficax, quia datur loco & tempore congruo. Etsi enim certum sit, gratiam congruam & efficacem non nisi tempore congruo dari; ejus tamen congruitatem & efficaciam a tempore potissimum desumendam non esse; sed in vocatione ipsa assignandum aliquid, propter quod tali tempore & loco effectum est habitura: siquidem alia vocatio, etsi sufficiens, eodem illo tempore nihil proficeret. Ideoque ex ejus sensu, Congruitas illa gratiae nihil est aliud quam proportio quaedam, & accommodatio inter gratiam ipsam, & voluntatem sic affectam, ut infallibiliter sequatur operatio. Disput. 7. Sect. 9. num. 66.