But there is only one child that
is first-born and holy before the Lord, the one whose conception took place not
through desire and the male seed—certainly not!—but through grace and the coming
of the Holy Spirit, and his birth took place not in corruption and pain but
through the power and wisdom of the most high God. That is why the child was
born holy, and the Holy of Holies according to the words of Isaiah. (Maximus
the Confessor, The Life of the Virgin 47 [trans. Stephen J. Shoemaker;
New Haven: Yale University Press, 2012], 76 [do note: in Catholic and Eastern Orthodox tradition, Mary was an only child)