Full Idea
Nature only clamours for two things, a body free from pain, a mind released from worry and fear for the enjoyment of pleasurable sensation.
Gist of Idea
Nature only wants two things: freedom from pain, and pleasure
Source
Lucretius (On the Nature of the Universe [c.60 BCE], II.21)
Book Reference
Lucretius: 'On the Nature of the Universe', ed/tr. Latham,Ronald [Penguin 1951], p.60
A Reaction
I can't help agreeing with those (like Aristotle) who consider this a very demeaning view of human life. See Idea 99. Bentham agrees with Lucretius (Idea 3777). I think they are largely right, but not entirely. Other motives are possible than sensations.
Related Idea
Idea 3777 Pleasure and pain control all human desires and duties [Bentham]