Did any Catholic theologians think that the prophecy of Is. 7:14 ("Behold a virgin shall conceive, and bear a son, and his name shall be called Emmanuel.") inspired the Blessed Virgin to take a vow of virginity?
St. Elisabeth of Schönau, O.S.B. (1129-1164) received this ecclesiastically-approved private revelation, quoted in The Life of Mary as Seen by the Mystics ch. 5 "In the Temple":
Once when I [Mary] was thinking that I never wanted to be deprived of God’s grace, I arose and went to read in the Scriptures, desiring something to console my soul. When I opened the book, the first thing I saw was this passage of Isaias [7:14]: “Behold a virgin shall conceive and bear a son.” As I understood from this that the Son of God was going to choose a virgin to be His Mother, I immediately resolved in my heart, out of reverence for that virgin, to remain a virgin myself and to offer myself to her as a handmaid and always to serve her and never to leave her, even if I had to travel all over the world with her.