“Grace presupposes nature, we say, because only with a true rational nature can man act toward God. Only with his own real capacity of action can man enter into a real friendship with him. The life of grace means precisely entering into friendship with the divine persons, and this means being able to receive the gift of God’s love with full awareness and knowledge of the absolute freedom and gratuity of the gift. God’s self-giving in grace is certainly gratuitous, and thus truly a love on his part. It must be received in the same way by the creature, man. He must be able to recognize God’s love as a gift, and must be able to respond to him freely and in love, that is, as a person.
If man, then, must be a personal spirit able to exist and act on the foundation of a natural structure and reality, he must also be open to the personal invitation of God’s love. He must have a capacity for the infinite; he must be a being not closed in upon himself but able to go out in knowledge and love to a personal encounter with the personal God. The natures of created beings lesser than man are not open in this way to God, for lower creatures cannot transcend themselves; they are enclosed, in a sense, in their own natural being. But by his nature, man is capable of going out of himself to meet God. He is created in such a way as to be able to enter into relationship with the divine persons. Not only is man capable of this in an absolute sense; he is so constituted that he can welcome God in virtue of his own deepest longings and desires.
This does not mean in any sense that man’s natural structure or dynamism of action demands the personal gift of divine love. Precisely the opposite holds true, for man in his nature and activity must be capable of receiving God’s gift as totally gratuitous. This means that man’s nature must be so genuinely self-consistent in its constitution so that it does not demand grace by any sort of natural necessity. Rather the inner reality of nature must be such as to allow man to be truly man, and thus to be capable of responding to God’s love freely and without any inner exigency or compulsion. Catholic theology, in maintaining this position, respects not only the genuine being of man but also the gratuity and supernatural character of the divine personal gift. The very transcendence of the gift demands the reality of nature, which is to say that the proper appreciation of the order of grace involves an accurate view of the structure of nature.
If, then, human nature does not demand grace, it is yet open to grace, and this in a unique way not shared by any work of creation below it. This openness is shown in the capacity of man for a knowledge of the reality of being and in his ability to love reality as good. Man’s abilities to know and to love find their proper field of exercise in the world of created beings, but in their activity they manifest the power to go beyond the individual realities of this world. Human love, too, can never be fully satisfied with the goodness of individual creatures.
Man’s powers of knowledge and love thus manifest a capacity which is not limited by this world. For this reason the gift of God himself can be received by man and welcomed as the ultimate and absolute fulfillment of his deepest longings. Man is constituted in such a way as to be truly a self-consistent being, but at the same time he is a personal spirit capable of being elevated to the order of grace. He can receive the gift of God as the ultimate perfection of his nature and as the gratuitous beneficence of divine love, a reality wholly beyond the demands and expectations of his nature.”
-P. Gregory Stevens, OSB in The Life of Grace.