Allusion
Alluding to the classic literature of the past is a popular means of introducing metaphor into any story. Of course, if the person reading is not familiar with the allusion, the comparison via simile tends to fall apart. Then again, at the time Juvenal was writing, there really wasn’t all that much existing literature to refer back to. In this case, Juvenal depends on the familiarity of one of the most famous characters in myth:
"Your drunken bully who has by chance not slain his man passes a night of torture like that of Achilles when he bemoaned his friend, lying now upon his face, and now upon his back”
Obscure Allusion
At the other end of the spectrum as it relates to literary allusions as metaphor is this example. While a great many people at least recognize the name Achilles, even that basic level of familiarity is missing from this next metaphor. For clarity’s sake, it is a comparison to a satyr who was flayed by one of the most famous gods of ancient myth, Apollo:
“I should like to know, Naevolus, why you so often look gloomy when I meet you, knitting your brow like a vanquished Marsyas.”
Sage Advice
The Satires are filled with sage advice. This advice is often—very, very often—phrased in the form of a metaphor. Fortunately, these examples of metaphor are usually easy enough to parse and don’t involved obscure or even familiar literary allusions:
“It is a poor thing to lean upon the fame of others, lest the pillars give way and the house fall down in ruin.”
Poetic Imagery
The metaphor is perhaps most closely associated with poetic imagery. The comparison made without the “like” or “as” of a simile has a certain fluidity to it when used well to the point that it can become poetry even in the midst of prose:
“Many a man has met death from the rushing flood of his own eloquence; others from the strength and wondrous thews in which they have trusted.”
Note: “thews” is itself a kind of metaphorical term associating anatomical structures like muscles and tendons with physical strength.
Symbolism
Technically, metaphors and similes are a kind of symbolism. But this is not necessarily always the case. In some instances, however, the comparison within the simile is quite explicitly symbolic. In this example, the specific symbol within the metaphorical imagery is that of the white crow.
“The Fates will give kingdoms to a slave, and triumphs to a captive! Nevertheless that fortunate man is rare—rarer than a white crow.”
