Sin

"Sin aims always at the utmost; every time it rises up to tempt or entice, might it have its own course, it would go out to the utmost sin in that kind. Every unclean thought or glance would be adultery if it could; every covetous desire would be oppression, every thought of unbelief would be atheism, might it grow to its head... it is like the grave, that is never satisfied (Prov. 27:20)"

From Mortification of Sin, by John Owen.