Full Idea
The desires and other passions of man are in themselves no sin. No more are the actions that proceed from those passions, till they know a law that forbids them.
Clarification
'Law' is the Greek word 'nomos', which also translates as 'convention'
Gist of Idea
Men's natural desires are no sin, and neither are their actions, until law makes it so
Source
Thomas Hobbes (Leviathan [1651], 1.13)
Book Reference
Hobbes,Thomas: 'Leviathan', ed/tr. Macpherson,C.B. [Penguin 1981], p.187
A Reaction
That is a pretty flat rejection of natural law, as you might expect from an empiricist. So prior to the first law-making, no one ever did anything wrong? Hm.