Full Idea
No single element [of the soul] can be separated, nor can their capacities be divided spatially; they are like the multiple powers of a single body
Gist of Idea
The separate elements and capacities of a mind cannot be distinguished
Source
Lucretius (On the Nature of the Universe [c.60 BCE], III.262), quoted by A.A. Long - Hellenistic Philosophy 2.7
Book Reference
Long,A.A.: 'Hellenistic Philosophy' [Duckworth 1986], p.51
A Reaction
It is interesting that this comes from someone with a strongly physicalist view of the mind (though not, if I recall, focusing on the brain). He is still totally impressed by the unified phenomenology of mental experience. He is an empiricist.