The Principle of all Good According to Saint Ireneus

"Why did the Divine Word not want to take flesh in Mary's womb before obtaining her consent," wondered Saint Ireneus, through the angel?

It's because He wanted the whole world to be indebted to Mary for the
mystery of the Incarnation and "recognize in her the beginning of all
good."

(Contra haereses, lib. III, cap. XXII, n°4 et lib. V, cap. XIX, n°I - mentioned
in The Glories of Mary by Saint Alphonsus de Liguori)