Do you suffer your thoughts to tamper with evil; and to dally with wrong-doing? If so; you are not sincere. God will regard your thoughts; for thoughts are heard in heaven. If you willingly sin in thought; if you are base and guilty there; because you think that no eye will see your thoughts; the guilt and baseness will sooner or later break into the outlets of word and deed — from thought to wish — from wish to purpose — from purpose to word — from word to act — from act to habit — from delight in the imagination to consent in the will — from deed to repeated transgression; such is the genesis of sin.
Frederick Farrar quotes