Two short excerpts from Luther’s essay on The Magnificat:
From this we may learn how to show her the honor and devotion that are her due. How ought one to address her? Keep these words in mind, and they will teach you to say: “O Blessed Virgin, Mother of God, you were nothing and all despised; yet God in His grace regarded you and worked such great things in you. You were worthy of none of them, but the rich and abundant grace of God was upon you, far above any merit of yours. Hail to you! Blessed are you, from thenceforth and forever, in finding such a God.”
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The word μακαριου̂σι means more than simply “to call blessed”; its meaning is rather “to bless,” or to “make blessed.” This consists not merely in saying the words, bending the knee, bowing the head, doffing the hat, making images, or building churches; for this even the wicked can do. But it is done with all one’s strength and with downright sincerity, when the heart, moved by her low estate and God’s gracious regard of her, as we have seen, rejoices in God and says or thinks with all its heart, “O Blessed Virgin Mary!” So to bless her is to accord her the honor that is her due, as we have seen.