Does Our Lady distribute grace only in the sense that she intercedes for each one of us and so obtains that the fruits of the merits of her Son be applied to each one of us at the appropriate moment, or does she transmit graces to us in the way in which the Sacred Humanity does? According to the teaching of St. Thomas and many other theologians, the Sacred Humanity is a physical instrumental cause of grace, an instrument always united to the divinity and higher than the sacraments, which are instruments separated from the divinity.
St. Thomas has treated of this question in many places in so far as it refers to Christ, the Head of the Church (1). It is but reasonable to ask if something similar to what he says about the Head may be affirmed of her who is, according to the teaching of Tradition, as it were the neck of the Mystical Body which unites the Head to the members and transmits the vital impulse to them.
In this connection theologians commonly admit that Mary exercises moral causality by her past merits and satisfaction and by her present intercession. But very many stop there and do not admit that she exercises any physical instrumental causality (2). Other theologians admit physical instrumental causality in subordination to the Sacred Humanity. They rely in support of their thesis on the traditional doctrine of Mary as the neck of the Mystical Body, uniting Head and members, and transmitting the vital influence to them (3).
It is certain that St. Thomas taught explicitly that the Sacred Humanity and the sacraments of the New Law are physical instrumental causes of grace. God alone is its principal cause, since it is a participation in his inner life. But there is no similar statement of his about Our Lady. There are even theologians—with whom we do not agree—who hold that he explicitly denied her any such causality (4). In his explanation of the Ave Maria, he attributes to Mary a fullness of grace which overflows on souls and sanctifies them, but he does not say explicitly that this overflowing is anything more than moral causality.
However, since physical instrumental causality was not an impossibility for the Sacred Humanity nor for the sacraments—for example, for the words of the priest at the consecration or when giving absolution—in the opinion of St. Thomas and his commentators, neither is it an impossibility for Mary (5). St. Thomas even admits that a miracle-worker is sometimes instrumental cause of a miracle, for example, when it is worked through a blessing (6). Not only can he obtain the miracle by his prayer, he may even perform it as God’s instrument.
It is not possible therefore to be certain that Mary did not exercise a similar influence in regard to grace. We must also allow for the fact that God’s masterpieces—among which we must include Mary—are richer, more beautiful, more brimful of life than we can find words to describe.
But at the same time it must be admitted that it does not seem possible to prove with certainty that Mary did exercise physical causality. Theology will hardly advance beyond serious probability in this matter for the reason that it is very hard to see in the traditional texts quoted where precisely the literal sense ends and the metaphorical sense begins. Those who are in the habit of using metaphors whenever they can will not appreciate this difficulty. But anyone who is accustomed to using words in their exact and proper sense will be fully sensible of it. When Tradition tells us that Mary’s position i