-- Jn 3:7b-15
At once virgin and mother, Mary is the symbol and the most perfect realization of the Church: "the Church indeed. . . by receiving the word of God in faith becomes herself a mother. By preaching and Baptism she brings forth sons, who are conceived by the Holy Spirit and born of God, to a new and immortal life. She herself is a virgin, who keeps in its entirety and purity the faith she pledged to her spouse."
-- CCC 507
The symbolism of water signifies the Holy Spirit's action in Baptism, since after the invocation of the Holy Spirit it becomes the efficacious sacramental sign of new birth: just as the gestation of our first birth took place in water, so the water of Baptism truly signifies that our birth into the divine life is given to us in the Holy Spirit. As "by one Spirit we were all baptized," so we are also "made to drink of one Spirit." Thus the Spirit is also personally the living water welling up from Christ crucified as its source and welling up in us to eternal life.-- CCC 694
(Art: St Peter and Cornelius the centurion, Bernardo Cavallino, 1640s, oil on canvas, Galleria Nazionale d'Arte Antica, Roma.)