Newman, in his letter to Pusey, writes thus of the Immaculate Conception:
It is then an integral portion of the Faith fixed by Ecumenical Council, a portion of it which you hold us well as I, that the Blessed Virgin is Theotocos, Deipara, or Mother of God; and this word, when thus used, carries with it no admixture of rhetoric, no taint of extravagant affection,—it has nothing else but a well-weighed, grave, dogmatic sense, which corresponds and is adequate to its sound. It intends to express that God is her Son, as truly as any one of us is the son of his own mother. If this be so, what can be said of any creature whatever, which may not be said of her? what can be said too much, so that it does not compromise the attributes of the Creator? He indeed might have created a being more perfect, more admirable, than she is; He might have endued that being, so created, with a richer grant of grace, of power, of blessedness: but in one respect she surpasses all even possible creations, viz., that she is Mother of her Creator. It is this awful title, which both illustrates and connects together the two prerogatives of Mary, on which I have been lately enlarging, her sanctity and her greatness. It is the issue of her sanctity; it is the origin of her greatness. What dignity can be too great to attribute to her who is as closely bound up, as intimately one, with the Eternal Word, as a mother is with a son? What outfit of sanctity, what fulness and redundance of grace, what exuberance of merits must have been hers, when once we admit the supposition, which the Fathers justify, that her Maker really did regard those merits, and take them into account, when He condescended "not to abhor the Virgin's womb"? Is it surprising then that on the one hand she should be immaculate in her Conception?
The Belief of Catholics concerning the Blessed Virgin, as distinct from their Devotion to her