The Evangelist has expressed himself cautiously; not struck, or wounded, but opened His side: (ἔνυξε, aperuit V.) whereby was opened the gate of life, from whence the sacraments of the Church flowed, without which we cannot enter into that life which is the true life: And forthwith came thereout blood and water. That blood was shed for the remission of sins, that water tempers the cup of salvation. This it was which was prefigured when Noah was commanded to make a door in the side of the ark, by which the animals that were not to perish by the deluge entered; which animals prefigured the Church. To shadow forth this, the woman was made out of the side of the sleeping man; for this second Adam bowed His head, and slept on the cross, that out of that which came therefrom, there might be formed a wife for Him. O death, by which the dead are quickened, what can be purer than that blood, what more salutary than that wound!
Reproduced in full. Translation: Oxford 1841 (Newman), public domain (Public domain).
Also cites: Tr. cxx.