Today's Quintilian: 8.6.28

XXVIII. Est etiam huic tropo quaedam cum synecdoche vicinia; nam cum dico "vultus hominis" pro vultu, dico pluraliter quod singulare est: sed non id ago, ut unum ex multis intellegatur (nam id est manifestum), sed nomen inmuto: et cum aurata tecta "aurea", pusillum ab ea discedo, quia non est pars auratura. Quae singula persequi minutioris est curae etiam non oratorem instruentibus.

28. The following kind of trope has also some affinity with the synecdoche. When I say vultus hominis, "the looks of a man," I express in the plural that which is singular. Yet I do not make it my object that one may be understood out of many (for my meaning is evident), but make an alteration only in the term. When I call, also, gilded ceilings "golden ceilings," I deviate a little from the truth, as the gilding is but a part. To notice all such expressions, however, would be too trifling an employment, even for those who are not forming an orator.