They have said that we deify her; that is not because we exaggerate the eminence of God's Mother, but because they belittle the eminence of God. A creature miraculously preserved from sin by the indwelling power of the Holy Ghost -- that is to them a divine title, because that is all the claim their grudging theologies will concede, often enough, to our Lord Himself. They refuse to honor the God- bearing Woman because their Christ is only a God-bearing Man. We who know that God could (if He would) annihilate every existing creature without abating anything of His blessedness or His glory, are not afraid less the honor done to His creature of perfect Womanhood should prejudice the honor due to Him. Touchstone of truth in the ages of controversy, romance of the medieval world, she has not lost with the rise of new devotions, any fragment of her ancient glory. Other lights may glow and dim as the centuries pass, she cannot suffer change; and when a Catholic ceases to honor her, he ceases to be a Catholic.
---Msgr. Ronald Knox, The Belief of Catholics