Full Idea
Mind and spirit are both composed of matter, as we see them propelling limbs, rousing the body from sleep, changing the expression of the face, and guiding the whole man - activities which clearly involves touch, which involves matter.
Gist of Idea
The mind moves limbs, wakes the body up, changes facial expressions, which involve touch
Source
Lucretius (On the Nature of the Universe [c.60 BCE], III.164)
Book Reference
Lucretius: 'On the Nature of the Universe', ed/tr. Latham,Ronald [Penguin 1951], p.101
A Reaction
This is the inverse of Descartes' interaction problem, and strikes me as a straightforward common sense truth. However, if you believe in spiritual gods, this gives you a model for the interaction (however mysterious) of matter and spirit.