The same divine authority that forbids the killing of a human being establishes certain exceptions, as when God authorizes killing by a general law or when He gives an explicit commission to an individual for a limited time.
The Holy Scriptures are our letters from home.
He who has God has everything; he who has everything but God has nothing.
In doing what we ought we deserve no praise, because it is our duty.
No one can have God as his father who does not have the Church as his mother.
Recognize in this bread what hung on the cross, and in this chalice what flowed from His side... whatever was in many and varied ways announced beforehand in the sacrifices of the Old Testament pertains to this one sacrifice which is revealed in the New Testament.