Mary is called in the sacred Canticles the Tower of David: Thy neck is as the tower of David; a thousand bucklers hang upon it; all the armor of valiant men. St. Bernardine says, that the tower of David stood on high, that is, on Sion; therefore Mary is called the tower of David, to denote the height of the perfection of this great creature: “As Sion was a very elevated spot, so was the Blessed Virgin most exalted.” Therefore of Mary it is said in the Psalms, that the very beginning of her sanctity was more exalted than the mountains: The foundations therefore are in the holy mountains: St. Gregory explains it to mean that the divine Mother was more holy in the first moment of her life than any of the saints were at the moment of their death.
Ah, my Queen and Mother, I rejoice in thy greatness, and am willing rather to sacrifice my life than that thy glory should be diminished in the least degree, were such a thing possible. O that I could only by shedding every drop of my blood cause all nations of the earth to adore and love thee as the great Lady which thou art!
From The Glories of Mary by St. Alphonsus de Liguori