Full Idea
Whosoever look on a woman to lust after her hath committed adultery with her already in his heart.
Gist of Idea
If you lust after a woman, you have committed adultery
Source
Jesus (reports [c.32]), quoted by St Matthew - 01: Gospel of St Matthew 05.28
Book Reference
'The Bible', ed/tr. the Church [Collins 1950], p.459
A Reaction
Compare Democritus, Idea 503. Literally this idea seems absurd, but it is also at the heart of Greek virtue theory. Aristotle (Idea 34) defines virtue as an activity 'of the soul', not an action in the world. Excellence has become purity of soul.
Related Idea
Idea 503 Virtue doesn't just avoid evil, but also doesn't desire it [Democritus (attr)]