We proceed to the ninth article thus:

1. It seems that one who has already received grace can do good and avoid sin by himself, without further help of grace. For if anything does not achieve that for which it is given, either it is given in vain, or it is imperfect. Now grace is given to enable us to do good and avoid sin. Hence if one who has received grace is unable to do this, either grace is given in vain, or it is imperfect.

2. Again, the Holy Spirit dwells in us by grace, according to I Cor.3:16: "Know ye not that ye are the temple of God, and that the Spirit of God dwelleth in you?" Now the Holy Spirit is omnipotent, and therefore sufficient to make us do good and to keep us from sin. It follows that a man who has received grace can do both of these things, without further help of grace.

3. Again, if a man who has received grace needs further help of grace in order to live rightly and avoid sin, by the same reasoning he will need yet further help of grace after receiving this further grace, and so on to infinity, which is impossible. One who is already in grace, therefore, does not need further help of grace in order to do good and avoid sin.

On the other hand: Augustine says {De Nat. et Grat.26): "just as even the healthiest eye of the body cannot see unless aided by the radiance of light, so even the most perfectly-justified man cannot live rightly unless aided by the eternal light of heavenly righteousness." Now justification is by grace, according to Rom.3.24: "Being justified freely by his grace." Hence even a man who has already received grace needs further help of grace in order to live rightly.

I answer: as we said in Art.5, a man needs help from God in two ways, in order to live rightly. First, he needs a habitual gift by which his corrupt nature may be healed, and thereafter raised to perform works such as merit eternal life, which exceed what is commensurate with his nature. Secondly, he needs the help of grace by which God moves him to act. Now a man already in grace does not need further grace in the form of another infused habit. But there are two reasons why he needs the help of grace in the second way, if he is to act rightly. He needs it for the general reason that no creature can act at all except by the divine moving, as we said in the first article. He also needs it for the special reason that the natural condition of human nature remains corrupt and infected in the flesh, with which it serves the law of sin, according to Rom.7:25, even though it be healed in the spirit through grace. There remains also a darkness of ignorance in the intellect, on account of which "we know not what we should pray for as we ought," as it is said in Rom.8:26. We cannot fully know what is for our good, because of the unpredictable course of events, and because we do not even know ourselves perfectly. As it is said in Wisdom 9:14: "the deliberations of mortals are hesitant, and our counsels uncertain." We must therefore be guided and protected by God, who knows and can do all things. Hence even those who are reborn through grace as sons of God ought to pray "and lead us not into temptation," and also "Thy will be done on earth, as it is in heaven," and whatever else in the Lord's prayer is relevant.

On the first point: a gift of habitual grace is not given so that we may dispense with any further divine help, since every creature must be preserved by God in the good which it receives from him. We cannot then conclude that grace is given in vain, or that it is imperfect, from the fact that a man in grace needs divine help in this way. A man will need divine help even in the state of glory, when grace will be perfect in every sense, whereas in this life grace is in one sense imperfect, in that it does not heal a man entirely, as we have said.

On the second point: the operation of the Holy Spirit, which inspires and perfects us, is not confined to the provision of the habitual gift which it causes in us. Together with the Father and the Son, it also inspires and protects us.

On the third point: this reasoning shows that a man needs no further habitual grace.