Institutio Oratoria

Quintilian

Quintilian. Institutio Oratoria, Volume 1-4. Butler, Harold Edgeworth, translator. Cambridge, Mass; London: Harvard University Press, William Heinemann Ltd., 1920-1922.

These four kinds of metaphor are further subdivided into a number of species, such as transference from rational beings to rational and from irrational to irrational and the reverse, in which the method is the same, and finally from the whole to its parts and from the parts to the whole. But I am not now teaching boys: my readers are old enough to discover the species for themselves when once they have been given the genus.

While a temperate and timely use of metaphor is

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a real adornment to style, on the other hand, its frequent use serves merely to obscure our language and weary our audience, while if we introduce them in one continuous series, our language will become allegorical and enigmatic. There are also certain metaphors which fail from meanness, such as that of which I spoke above [*](See VIII. iii. 48.) :
  1. There is a rocky wart upon the mountain's
  2. brow.
or they may even be coarse. For it does not follow that because Cicero was perfectly justified in talking of
the sink of the state,
[*]( In Cat. I. v. 12. ) when he desired to indicate the foulness of certain men, we can approve the following passage from an ancient orator:
You have lanced the boils of the state.

Indeed Cicero [*](De Or. iii. xli. 164. ) himself has demonstrated in the most admirable manner how important it is to avoid grossness in metaphor, such as is revealed by the following examples, which he quotes:—

The state was gelded by the death of Africanus,
or
Glaucia, the excrement of the senate-house.