If the plurality of types of figures seems prohibitive, the number of actual examples is overwhelming. This is because examples of figures crop up constantly in daily speech, and are employed universally—unconsciously and automatically for the most part—to compose new jargons, argots, and cants; or slangs, regional idioms, and even professional "languages". Poerty, purportedly, embodies the most colorful use of this non-literal way of speaking. But even when we say "My computer crashed" or "There's a bug in my program" we certainly do not expect a broken headlight in the first case or a cockroach in the computer in the second. Or if you tell someone to "chill out", you don't expect to detect a change in body temperature if they do chill out. Nor does being "taken beyond the walnut tree" imply any change of location. These are all just metaphorical expressions that have been coined with the mint of figures, and have caught on and become part of our language. There are thousands of such expressions in the language at any given time, and with each passing year new ones are forged and old ones fade away.

Humans naturally express new ideas metaphorically; and the drift of idioms through a language—though slow compared to a lifetime—is swift in historical terms. For this reason, books of idioms, though useful from an historical standpoint, miss the point of figurative language. By the time these kinds of books are published, many of the idioms that they contain are out of fashion. Nevertheless, some idioms do become a "permanent" part of the language, and are therefore stock in trade for the rhetor. They constitute in part the tools of Rhetoric. The concept of topoi ('topics') and koinoi topoi (commonplaces) for the most part refer to larger pieces of traditional speeches/arguments/cases; but idioms themselves certainly count as snippets of past "speakings", if not snippets of past "speeches".¹⁴ And as part of our cultural heritage—which in its totality is the real source of topoi—idioms deserve our consideration, not to mention our exploitation. Granted, common figures of speech are liable to become cliché, and their use can thus be problematic; but when used with care, the right figure can certainly drive the point home.