Whether a man, by himself and without the external aid of grace, can prepare himself for grace?

Objections

Objection 1 : It would seem that man, by himself and without the external help of grace, can prepare himself for grace. For nothing impossible is laid upon man, as stated above (Article [4], ad 1). But it is written (Zach. 1:3): "Turn ye to Me . . . and I will turn to you." Now to prepare for grace is nothing more than to turn to God. Therefore it seems that man of himself, and without the external help of grace, can prepare himself for grace.
Objection 2 : Further, man prepares himself for grace by doing what is in him to do, since if man does what is in him to do, God will not deny him grace, for it is written (Mt. 7:11) that God gives His good Spirit "to them that ask Him." But what is in our power is in us to do. Therefore it seems to be in our power to prepare ourselves for grace.
Objection 3 : Further, if a man needs grace in order to prepare for grace, with equal reason will he need grace to prepare himself for the first grace; and thus to infinity, which is impossible. Hence it seems that we must not go beyond what was said first, viz. that man, of himself and without grace, can prepare himself for grace.
Objection 4 : Further, it is written (Prov. 16:1) that "it is the part of man to prepare the soul." Now an action is said to be part of a man, when he can do it by himself. Hence it seems that man by himself can prepare himself for grace.