Institutio Oratoria

Let us begin, then, with the commonest and by far the most beautiful of tropes, namely, metaphor, the Greek term for our translatio. It is not merely so natural a turn of speech that it is often employed unconsciously or by uneducated persons, but it is in itself so attractive and elegant that however distinguished the language in which it is embedded it shines forth with a light that is all its own.

For if it be correctly and appropriately applied, it is quite impossible for its effect to be commonplace, mean or unpleasing. It adds to the copiousness of language by the interchange of words and by borrowing, and finally succeeds in accomplishing the supremely difficult task of providing a name for everything. A noun or a verb is transferred from the place to which it properly belongs to another where there is either no literal term or the transferred is better than the literal.

We do this either because it is necessary or to make our meaning clearer or, as I have already said, to produce a decorative effect. When it secures none of these results, our metaphor will be out of place. As an example of a necessary metaphor I may quote the following usages in vogue with peasants when they call a vinebud gemma, a gem (what other term is there which they could use?), or speak of the crops being thirsty or the fruit suffering. For the same reason we speak of a hard or rough man, there being no literal term for these temperaments.