Tertullian, On Baptism 9

How many natural defenses, how many gracious privileges, how many ritual solemnities, how many figures, prefigurings, and prayers have established the sacrality of water? First, when the people marched out of Egypt and crossed the sea, the water let them escape Pharaoh's power, then turned and drowned him with his entire army (Exodus 14:28). What figure could more clearly prefigure the sacrament of Baptism? Nations are freed from the world through water, leaving the devil, their former master, crushed beneath the waves. Again, when bitterness poisoned the water, Moses' wood healed it, restoring sweetness (Exodus 15:25). That wood was Christ, who from himself cures the toxic, bitter veins of our fallen nature with the waters of Baptism. This is the water that flowed from the rock that accompanied the people (Exodus 17:6). If the rock is Christ, then beyond doubt the water in Christ is blessed for Baptism. How vast is water's grace before God and his Christ for confirming Baptism! Christ is never without water, since he himself was baptized. He inaugurated the first display of his power at a wedding by turning water into wine (John 2:1-11). When he speaks, he invites the thirsty to his eternal water (John 4:14). When he teaches on love, he counts a cup of water offered to a brother among the works of love. At the well he regains his strength; he walks gladly on the water, crosses it, serves water to his disciples. He maintains the testimony of Baptism all the way to his passion. When he is handed over to the cross, water intervenes — Pilate's hands know it. When he is pierced, water bursts from his side — the soldier's lance knows it (John 19:34).