Book 8
6.23
It is but a short step from synecdocheè to metonymy, which consists in the substitution of one name for another, and, as Cicero Orat. xxvii. 93. tells us, is called hypallage by the rhetoricians. These devices are employed to indicate an invention by substituting the name of the inventor, or a possession by substituting the name of the possessor. Virgil, for example, writes: Aen. i. 177. Ceres by water spoiled, and Horace: Neptune admitted to the land Protects the fleets from blasts of Aquilo. A. P. 63. If, however, the process is reversed, the effect is harsh.
6.24
But it is important to enquire to what extent tropes of this kind should be employed by the orator. For though we often hear Vulcan used for fire and to say vario Marte pugnatum est for they fought with varying success is elegant and idiomatic, while Venus is a more decent expression than coitus, it would be too bold for the severe style demanded in the courts to speak of Liber and Ceres when we mean bread and wine. Again, while usage permits us to substitute that which contains for that which is contained, as in phrases such as civilised cities, or a cup was drunk to the lees, or a happy age,
