Thomas Aquinas

“ The material sun sheds its light outside us; but the intelligible Sun, Who is God, shines within us. Hence the natural light bestowed upon the soul is God's enlightenment, whereby we are enlightened to see what pertains to natural knowledge ”

“ The natural reason is not the sufficient principle of the health that is in man by justifying grace. This principle is grace which is taken away by sin. Hence man cannot be restored by himself; but he requires the light of grace to be poured upon him anew, as if the soul were infused into a dead body for its resurrection. ”

“ Hence we must say that for the knowledge of any truth whatsoever man needs Divine help, that the intellect may be moved by God to its act. But he does not need a new light added to his natural light, in order to know the truth in all things, but only in some that surpass his natural knowledge. And yet at times God miraculously instructs some by His grace in things that can be known by natural reason, even as He sometimes brings about miraculously what nature can do. ”

“ Charity loves God above all things in a higher way than nature does. For nature loves God above all things inasmuch as He is the beginning and the end of natural good; whereas charity loves Him, as He is the object of beatitude, and inasmuch as man has a spiritual fellowship with God. Moreover charity adds to natural love of God a certain quickness and joy, in the same way that every habit of virtue adds to the good act which is done merely by the natural reason of a man who has not the habit of virtue. ”

“ But by sinning no one ceases to be a man. Hence it is still in his power to choose good or evil; and thus man can avoid sin without grace.
On the contrary, Augustine says (De Perfect Just. xxi) : "Whoever denies that we ought to say the prayer 'Lead us not into temptation' (and they deny it who maintain that the help of God's grace is not necessary to man for salvation, but that the gift of the law is enough for the human will) ought without doubt to be removed beyond all hearing, and to be anathematized by the tongues of all." ”

“ Art. 9 - Whether one who has already obtained grace, can, of himself and without further help of grace, do good and avoid sin? Objection 1: It would seem that whoever has already obtained grace, can by himself and without further help of grace, do good and avoid sin. For a thing is useless or imperfect, if it does not fulfil what it was given for. Now grace is given to us that we may do good and keep from sin. Hence if with grace man cannot do this, it seems that grace is either useless or imperfect. ”

“ Now, man, by force of his nature, can rise from illness to health, without the external help of medicine, since there still remains in him the principle of life, from which the natural operation proceeds. Hence it seems that, with equal reason, man may be restored by himself, and return from the state of sin to the state of justice without the help of external grace. ”

“ When it is said that nature cannot rise above itself, we must not understand this as if it could not be drawn to any object above itself, for it is clear that our intellect by its natural knowledge can know things above itself, as is shown in our natural knowledge of God. ”

“ Hence the mind of man still unweakened is not so much master of its act that it does not need to be moved by God; and much more the free-will of man weakened by sin, whereby it is hindered from good by the corruption of the nature. ”

“ And thus the human understanding has a form, viz. intelligible light, which of itself is sufficient for knowing certain intelligible things, viz. those we can come to know through the senses. Higher intelligible things of the human intellect cannot know, unless it be perfected by a stronger light, viz. the light of faith or prophecy which is called the "light of grace," inasmuch as it is added to nature. ”

“ For when man's heart is not so fixed on God as to be unwilling to be parted from Him for the sake of finding any good or avoiding any evil, many things happen for the achieving or avoiding of which a man strays from God and breaks His commandments, and thus sins mortally: especially since, when surprised, a man acts according to his preconceived end and his pre-existing habits, as the Philosopher says (Ethic. iii) ; although with premeditation of his reason a man may do something outside the order of his preconceived end and the inclination of his habit. ”

“ He incurs a stain, inasmuch as he forfeits the lustre of grace through the deformity of sin. Natural good is corrupted, inasmuch as man's nature is disordered by man's will not being subject to God's; and this order being overthrown, the consequence is that the whole nature of sinful man remains disordered. Lastly, there is the debt of punishment, inasmuch as by sinning man deserves everlasting damnation. ”

“ And hence after anyone has been justified by grace, he still needs to beseech God for the aforesaid gift of perseverance, that he may be kept from evil till the end of his life. For to many grace is given to whom perseverance in grace is not given. ”

“ Nevertheless it was easier for man to persevere, with the gift of grace in the state of innocence in which the flesh was not rebellious against the spirit, than it is now. For the restoration by Christ's grace, although it is already begun in the mind, is not yet completed in the flesh, as it will be in heaven, where man will not merely be able to persevere but will be unable to sin. ”

“ So, too, before man's reason, wherein is mortal sin, is restored by justifying grace, he can avoid each mortal sin, and for a time, since it is not necessary that he should be always actually sinning. ”

“ But wage or reward is meted by God to everyone according to his works, according to Ps. 61:12: "Thou wilt render to every man according to his works." Hence, since man is master of his works, it seems that it is within his power to reach everlasting life.
Objection 3: Further, everlasting life is the last end of human life. Now every natural thing by its natural endowments can attain its end. Much more, therefore, may man attain to life everlasting by his natural endowments, without grace. ”

“ Now since the Spirit of God is omnipotent, He is sufficient to ensure our doing good and to keep us from sin. Hence a man who has obtained grace can do the above two things without any further assistance of grace. ”

“ And hence no matter how perfect a corporeal or spiritual nature is supposed to be, it cannot proceed to its act unless it be moved by God; but this motion is according to the plan of His providence, and not by necessity of nature, as the motion of the heavenly body. Now not only is every motion from God as from the First Mover, but all formal perfection is from Him as from the First Act. And thus the act of the intellect or of any created being whatsoever depends upon God in two ways: first, inasmuch as it is from Him that it has the form whereby it acts ”

“ And thus, even as inordinate movements of the sensitive appetite cannot help occurring since the lower appetite is not subject to reason, so likewise, since man's reason is not entirely subject to God, the consequence is that many disorders occur in the reason. ”

“ But what rests with our will, we can do of ourselves. Hence it seems that man can merit everlasting life of himself.
Objection 2: Further, eternal life is the wage of reward bestowed by God on men, according to Mat. ”

“ Now every form bestowed on created things by God has power for a determined act, which it can bring about in proportion to its own proper endowment; and beyond which it is powerless, except by a superadded form, as water can only heat when heated by the fire. ”

“ Man can do nothing unless moved by God, according to Jn. 15:5: "Without Me, you can do nothing." Hence when a man is said to do what is in him to do, this is said to be in his power according as he is moved by God. ”