In Act 1, Scene 5, Mosca reports back to Volpone that Corvino has a wife, Celia, of incalculable beauty. In a series of similes that rely on the imagery of light and whiteness, he relates her magnificence to his master:
O, sir, the wonder,
The blazing star of Italy! a wench
O’the first year! a beauty ripe as harvest!
Whose skin is whiter than a swan all over!
Than silver, snow, or lilies! a soft lip,
Would tempt you to eternity of kissing!
And flesh that melteth in the touch to blood!
Bright as your gold, and lovely as your gold!
Everything about Celia, in Mosca’s view, deserves a superlative description. The literary devices he uses to power this description—similes that compare Celia to a ripe harvest, to the feathers of a swan, to sparkling silver, snow, and a lily flower, as well as (most importantly) gold itself—all hinge on the brilliance of the objects: everything Mosca mentions is bright, sparkly, or otherwise glowing. In this way, the figurative language in this passage draws heavily on visual imagery.
The final comparison, between Celia and gold, is the most consequential. Mosca speaks to Volpone in the language he understands (the language of wealth), and he knows that gold is the thing that Volpone prizes over all other treasures. This description of Celia launches Volpone’s obsession with her that lasts for the greater part of the play, but the audience knows from this first moment of introduction that Volpone does not love Celia so much as he wants to possess her in the manner of his other treasures. In this way, Jonson reveals—and perhaps even critiques, with his satire—the way in which men could covet women as objects rather than people.
In Act 5, Scene 2, Mosca and Volpone reflect on their astounding day in court, during which they managed to deflect all blame for Volpone's attempted rape of Celia onto Celia and Bonario themselves. Wielding his considerable rhetorical skill, Mosca uses metaphor and imagery to describe their act of deception:
Mosca: Why, now you speak, sir! We must here be fixed;
Here we must rest. This is our masterpiece;
We cannot think to go beyond this.Volpone: True, Th’ ast played thy prize, my precious Mosca.
Mosca: Nay, sir, To gull the court—
Volpone: And quite divert the torrent Upon the innocent.
Mosca: Yes, and to make so rare a music out of discords—
The running metaphor Mosca uses for his works of manipulation and trickery is that of a work of theater, but here he invokes the imagery of music and musical performance—their success in court, Mosca insists, was a "masterpiece," a "rare [...] music out of discords." In this metaphor, the chaotic accusations that overlap and intersect between the various characters of the play as they begin to turn on one another are compared to discordant tones in a piece of music (and, by Volpone, to a "torrent" of water, as in a flood). Out of this "discord," Mosca has somehow managed—like a brilliant composer—to find a melody and to create his masterpiece.
A character's skill with language is the measure of their worth in Volpone, and over the course of the play Mosca emerges as an artist in his own right. As a wordsmith, Mosca can create his own realities through acts of artful deception that Jonson draws in parallel with his own composition of the play at large. It is this ability that lands Mosca in trouble with Volpone in the closing scenes of the play, and his talent will eventually be his undoing, as Volpone turns him in to the court.