12 For as Aquinas correctly states: "The Blessed Virgin, because she is the Mother of God, has a certain infinite dignity from the infinite good, which is God" (Cf. Summa Theologiae , I, Q, 25, Art 6 as 4um). And a distinguished writer develops and explains this in these words: "The Blessed Virgin . . . is the Mother of God: therefore, she is the purest and the most holy, so that under God a greater purity cannot be understood" (Cornelius a Lapide, In Matth. 1.16).
Source: Fulgens Corona (Vatican.va)