Full Idea
Where there is perception there is also pleasure and pain, and where there are these, of necessity also appetite.
Gist of Idea
Perception necessitates pleasure and pain, which necessitates appetite
Source
Aristotle (De Anima [c.329 BCE], 413b23)
Book Reference
Aristotle: 'De Anima (On the Soul)', ed/tr. Lawson-Tancred,H.C. [Penguin 1986], p.160