Full Idea
A person concerned with learning is concerned with purely mental pleasure, having nothing to do with pleasures reaching the mind through the body - assuming the person is a genuine philosopher.
Gist of Idea
Philosophers are concerned with totally non-physical pleasures
Source
Plato (The Republic [c.371 BCE], 485d)
Book Reference
Plato: 'Republic', ed/tr. Waterfield,Robin [OUP 1993], p.205
A Reaction
It is hard to find any argument which can demonstrate that mental pleasures are superior to physical ones. Mill notably failed to do it.