I was talking to EricR this morning and trying to remember the source of this quote. In tracking it down it seems to come from Porphyry's letter to Marcella -- but do we really know this is attributable to Epicurus? Usener seems to think so, but why? Anyone recall?
Porphyry, Letter to Marcella, 31, [p. 209, 23 Nauck]: Vain is the word of a philosopher which does not heal any suffering of man. For just as there is no profit in medicine if it does not expel the diseases of the body, so there is no profit in philosophy either, if it does not expel the suffering of the mind.