Aristotle,
Poetics
, ii. §26.
'The excellence of Diction consists in being perspicuous without being mean.'
Verum ubi plura nitent in carmine, non ego paucis
Offendar maculis, quas aut incuria fudit,
Aut humana parum cavit natura.
De Ar. Poet.
, II. 351-3.