Really great moral teachers never do introduce new moralities: it is quacks and cranks who do that.... The real job of every moral teacher is to keep on bringing us back, time after time, to the old simple principles which we are all so anxious not to see; like bringing a horse back and back to the fence it has refused to jump or bringing a child back and back to the bit in its lesson that it wants to shirk.
C. S. LewisThe monstrosity of sexual intercourse outside marriage is that those who indulge in it are trying to isolate one kind of union (the sexual) from all the other kinds of union which were intended to go along with it and make up the total union.
C. S. Lewis