Full Idea
Nothing can touch or be touched except body.
Gist of Idea
Only bodies can touch one another
Source
Lucretius (On the Nature of the Universe [c.60 BCE], I.303)
Book Reference
Lucretius: 'On the Nature of the Universe', ed/tr. Latham,Ronald [Penguin 1951], p.36
A Reaction
This is the key objection to interactionism, and the main reason why the atomists have a thoroughly material view of the mind. It is an induction from a very large number of instances, but the argument is not, of course, conclusive.