e) To physical predetermination or premotion in the order of nature, there corresponds in the supernatural sphere the _gratia efficax_, which predetermines man to perform salutary acts in such wise that he acts freely but at the same time with metaphysical necessity (_necessitate consequentiae_, not _consequentis_). It would be a contradiction to say that efficacious grace given for the purpose of eliciting consent may co-exist with non-consent, _i.e._, may fail to elicit consent.(717) The will freely assents to the divine impulse because it is effectively moved thereto by grace. Consequently, efficacious grace does not derive its efficacy from the consent of the will; it is efficacious of itself and intrinsically (_gratia efficax ab intrinseco sive per se_).(718) It follows that efficacious grace must be conceived as a _praedeterminatio ad unum_.(719) f) If efficacious grace is intrinsically and of its very nature inseparably bound up with the consent of the will, it must differ essentially from merely sufficient grace (_gratia mere sufficiens_), which confers only the power to act (_posse operari_), not the act itself (_actu operari_). Efficacious grace, by its very definition, includes the free consent of the will, while merely sufficient grace lacks that consent, because with it, it would cease to be merely sufficient and would become efficacious.(720) Here the question naturally arises: How, in this hypothesis, can sufficient grace be called truly sufficient? The Thomists answer this question in different ways. Gazzaniga says that sufficient grace confers the power to perform a good deed, but that something more is required for the deed itself.(721) De Lemos ascribes the inefficacy of merely sufficient grace to a defect of the will.(722) If the will did not resist, God would promptly add efficacious grace.(723) CRITICAL ESTIMATE OF THE THOMISTIC THEORY.—The Thomistic system undoubtedly has its merits. It is logical in its deductions, exalts divine grace as the prime factor in the business of salvation, and magnificently works out the concept of God as _causa prima_ and _motor primus_ both in the natural and the supernatural order. But Thomism also has its weak points. A. The Thomistic conception of efficacious grace is open to two serious theological difficulties. (1) To draw an intrinsic and substantial distinction between efficacious and merely sufficient grace destroys the true notion of sufficient grace. (2) The Thomistic theory of efficacious grace is incompatible with the dogma of free-will. Though in theory the Thomists defend the sufficiency of grace and the freedom of the will as valiantly as their opponents, they fail in their attempts at squaring these dogmas with the fundamental principles of their system.