John the Evangelist uses a carefully chosen word. He does not say that the soldier

“struck” Christ’s side or “wounded” it or anything else of the kind, but

that he “opened” it. This wording gives us a picture of the door of life opening

to let the sacraments of the Church flow out, those sacraments without which no one

can enter into life which is true life. The out poured Blood was poured out for the

remission of sins.

 

 The water is an ingredient of the cup of salvation : it serves both for washing and for drinking.

 

 All this was foreshadowed when Noe was commanded to make a door in the side of the ark. This door was to admit the living creatures who were not to perish in the flood: they prefigured the Church. To foreshadow the same mystery, the first woman was made from the side of the man as he slept, and she was called Life and Mother of the Living. Thus a great good was prefigured before the great evil of sin. Here the second Adam, bowing His head, slept on the cross, that a wife might be formed for Him out of the water and Blood that flowed from His side as He slept. 

 

O death, by which the dead return to life! What is more cleansing than this Blood? What is more health-giving than this wound?

 A homily of St. Augustine, Bishop