“Some Protestants still believe in the divinity of Christ. Hence they acknowledge that ‘the fruit of Mary is the real Son of God.’ But they wish to consider little, or even nothing, about the exceptional dignity, perfection, and activity of the Mother of God in the order of grace. In this respect they can hardly be distinguished from those who deny the divinity of Christ. This idea can be reduced to this formula; Mary is the Mother of God, but not the bride of God. Expressed thus, such a view is evidently unnatural and contradictory.
Therefore as the expression, the divinely bridal motherhood, possesses a great polemical dogmatic value, so it has also a great constructive theological value for the scientific explanation of the privileges of Mary.
The motherhood, regarded as a relation of the mother to her fruit, or as bodily relationship with Christ, is not of itself enough for our considering the divine motherhood the constituting principle of the only excellence of Mary’s person. Theologians express this thought by distinguishing an adequate and an inadequate, or a moral-physical and a purely physical, motherhood, and intend only the first to be considered that principle. They usually explain the motherhood in an adequate and moral-physical sense as follows: It consists in the whole of those graces which are necessary for the worthy execution of the maternal activity, or which were obtained through this activity, or which achieve the worthy extension of the relation of the mother to her fruit.
Such a widening of the idea of the motherhood will, no doubt, be too vague and indefinite. It will not produce a more vivid concept nor is it a fruitful middle term leading to the individual privileges that belong to the divine motherhood.
On the contrary, the very expression, God’s bridal motherhood, gives not merely a more or less adequate, moral-physical concept of the divine motherhood; according to its formal and intrinsic essence, the motherhood is also thus properly defined through an easily susceptible and clearly indicated element which is not lost in a multiplicity of things necessary or desirable for the worthy extension of the mother’s relation to the fruit. It constitutes, as it were, the substantial form or soul of that relation and therefore is the root and focus of all other qualities of the mother.
Without this middle concept we can only gradually and with difficulty discover the various privileges pertaining to the Mother of God, such as domina omnium. Of certain other privileges we can get hardly any idea; for example, of the sanctification of Mary through the grace of the motherhood. Thus this concept is the key of the entire Mariology.
In reference to the original marriage, Peter Chrysologous says: ‘A speedy interpreter (Gabriel) flies to the bride to prevent and suspend a state of human betrothal in the bride of God, not to take the Virgin away from Joseph, but to give her to Christ to whom she is pledged in her womb, when it should happen.’ And again: ‘Although Mary His mother had been betrothed, she is His bride by virginity, and His mother by fecundity; His mother not known by a man, and conscious of His birth. And was she not mother before her conceiving, who, after His birth, was both mother and virgin? And how could she not be mother, who brought to birth the Author of all the years, the Giver of being to all things?’”
-Matthias Scheeben in Mariology, vol. 1.