John Milton

They are not skilful considerers of human things, who imagine to remove sin by removing the matter of sin.… Though ye take from a covetous man all his treasure, he has yet one jewel left, ye cannot bereave him of his covetousness. Banish all objects of lust, shut up all youth into the severest discipline that can be exercised in any hermitage, ye cannot make them chaste, that came not hither so; such great care and wisdom is required to the right managing of this point. Suppose we could expel sin by this means; look how much we thus expel of sin, so much we expel of virtue: for the matter of them both is the same; remove that, and ye remove them both alike.