Spiritual Motherhood

On the floor of the Council, Pope Paul VI declared Mary Mother of the Church. This was not entirely new. Pius XII, in a message to the Marian Congress of Ottawa, Canada, on July 19, 1947 said: "When the little maid of Nazareth uttered her fiat to the message of the angel... she became not only the Mother of God in the physical order of nature, but also in the supernatural order of grace, she became the Mother of all, who... would be made one under the Headship of her Son. The Mother of the Head would be the Mother of the members."

taken from

The Blessed Virgin Mary: Her Privileges and Relation to Christ and His Church

https://www.ewtn.com/faith/teachings/marya1.htm

by Father William G. Most