Here is the quote from Philodemus:
Proper correction will come from one "actuated by good will, devoting himself intelligently and diligently to philosophy, steadfast in principle, careless of what people think of him, immune from any tendency to demagoguery, *** free from spitefulness***, saying only what fits the occasion, and not likely to be carried away so as to ***revile, jeer, belittle, injure feelings***, or resort to tricks of wanton acquiescence or flattery. - Philodemus of Gadara, On Frank Criticism I-b, 2-13