One observant, and very able, student some time ago was struck by the use of animal similes and metaphors by Aeschylus in Agamemnon: and he drew attention especially to one passage in Cassandra’s prophecy to the Chorus:
παπαῖ, οἷον τὸ πῦρ: ἐπέρχεται δέ μοι.
ὀτοτοῖ, Λύκει᾽ Ἄπολλον, οἲ ἐγὼ ἐγώ.
αὕτη δίπους λέαινα συγκοιμωμένη
λύκῳ, λέοντος εὐγενοῦς ἀπουσίᾳ,
κτενεῖ με τὴν τάλαιναν: ὡς δὲ φάρμακον
τεύχουσα κἀμοῦ μισθὸν ἐνθήσειν κότῳ
ἐπεύχεται, θήγουσα φωτὶ φάσγανον
ἐμῆς ἀγωγῆς ἀντιτείσασθαι φόνον.
¶ Oh! What fire! It is coming upon me!
Alas, Lycean Apollo! Ah me!
This two-footed lioness, mating
with a wolf in the absence of her noble lion,
will slay me, wretched that I am. As if making poison,
she vows in her wrath to bring reward on me also—
and, as she whets her blade for her husband,
to repay my coming here with murder.
—Agamemnon, lines 1256-63
To revisit Agamemnon is to be reminded of why Aeschylus was so venerated by his fellow Athenians. It is a play of extraordinary power, whose effects depend upon a nobility of language unlike that of any other writer; and the animal imagery, which is in it from beginning to end, so far from trivialising the events, raises them to a higher plane. The exchange between Cassandra and the Chorus is especially memorable, as this student discovered.
Longinus says: ‘The dignity, grandeur, and energy of a style largely depend on a proper employment of images.’—De Sublimitate XV.
English speech is generous of animal metaphor, and other languages use it too: Arabic, for example, has an array of such expressions. But it seems less frequent in classical Greek and Latin, insofar as we know much about common speech. Homer uses animal simile, but not metaphor.
It is commonplace in English. In a parliamentary debate, someone was heard to shout, “Dinosaur!” as a reprobative; and at the other extreme of size, tick and louse are first recorded in the seventeenth century. As for calling someone an ass—that goes back to before 1450.
Fat cats is an interesting one—originally an American expression, which the OED first records in the 1920s to mean the rich backers of political campaigns. But the other day it was heard in our Common Room describing money launderers. There is a tendency of language to move from the specific to the generic. Chambers records this more general use of fat cat: ‘a wealthy, prosperous person, esp. one who is thought to have gained excessive rewards.’
One sometimes hears of a man being called a love rat or a snake in the grass; and there are sharks. A woman might be called a cow or butterfly, or even a dragon. But a greedy hog seems to cover both sexes.