Full Idea
My concept of the human mind is a thinking thing, not extended in length, breadth or depth, and having nothing else from the body.
Gist of Idea
The mind is a non-extended thing which thinks
Source
René Descartes (Meditations [1641], §4.53)
Book Reference
Descartes,René: 'Discourse on Method/The Meditations', ed/tr. Sutcliffe,F.E. [Penguin 1968], p.132
A Reaction
But he admits (in Med 6) that the mind is so closely integrated with the body that they seem inseparable. Perhaps he shouldn't trust his own concept of the thing, because he is too close to the subject matter. You can't count a crowd if you are in it.