This interpretation is fully borne out by Tradition. St. Augustine, after laying it down as a general principle that “We can of ourselves do nothing to effect good works of piety without God either working that we may will, or co-operating when we will,”(350) says of justified man in particular: “The Heavenly Physician cures our maladies, not only that they may cease to exist, but in order that we may ever afterwards be able to walk aright,—a task to which we should be unequal, even after our healing, were it not for His continued help.... For just as the eye of the body, even when completely sound, is unable to see, unless aided by the brightness of light, so also man, even when fully justified, is unable to lead a holy life, unless he be divinely assisted by the eternal light of righteousness.”(351)
This agrees with the practice of the Church in exhorting all men without exception, saints as well as sinners, to pray: “Precede, we beseech Thee, O Lord, our actions by Thy holy inspiration, and carry them on by Thy gracious assistance, that every prayer and work of ours may begin always from Thee, and through Thee be happily ended.”(352)
b) Some theologians have been led by certain speculative difficulties to deny the necessity of actual grace in the state of justification.
Man in the state of justification, they argue, is endowed with sanctifying grace, the supernatural habits of faith, hope, and charity, and the infused moral virtues, and consequently possesses all those qualifications which are necessary to enable him to perform salutary acts with the supernatural concurrence of God. Why should the will, thus supernaturally equipped, require the aid of additional actual graces to enable it to perform strictly supernatural, and therefore salutary, actions?(353)
We reply: The necessity of actual grace in the state of justification is so clearly taught by divine Revelation that no theological theory is tenable which denies it. Besides, the objection we have briefly summarized disregards some very essential considerations, _e.g._ that there remains in man, even after justification, concupiscence, which is accompanied by a certain weakness that requires at least the _gratia sanans sive medicinalis_ to heal it.(354) Furthermore, a quiescent _habitus_ cannot set itself in motion, but must be determined from without; that is to say, in our case, it must be moved by the _gratia excitans_ to elicit supernatural thoughts and to will supernatural acts. Just as a seed cannot sprout without the aid of appropriate stimuli, so sanctifying grace is incapable of bearing fruit unless stimulated by the sunshine and moisture of actual graces. Man may perform purely natural acts even though he be in the supernatural state of grace; hence if any particular act of his is to be truly supernatural and conducive to eternal salvation, God must lend His special aid.(355)