Mosca is discovered in the street, soliloquizing on the nature, number, and the kinds of parasitic fools.
Once again, the act is divided into two locales. The first two scenes take place on a street. It is necessary that we become more completely acquainted with Mosca's disposition. Thus the third act opens with the traditional Elizabethan theatrical convention of the soliloquy.
In Mosca's address to the audience, Jonson displays a sound acquaintance with the history of the fool. There are parasites who subject themselves basely "to please the belly and the groin." There are others who fawn and make their voices as echoes to their lords. "But your fine, elegant rascal, that can rise and stoop, almost together, like an arrow," this "creature had the art born with him"; his kind are "the true parasites, others but their zanies." Furthermore, Mosca does not consider that his profession is an inferior one. Rather, "almost all the wise world is little else, in nature, but parasites or sub-parasites." Mosca is the equal of Volpone, Voltore, Corbaccio, and Corvino. It is not that he is able to rise to their noble position; they have made him their equal by descending to his lowly state. Jonson offers the audience a key to the comic philosophy of the play. The Elizabethan was acquainted with the profession of folly. There were two kinds of fools: the mentally and physically deformed fools of nature (for example, the dwarf, eunuch, and fool of Volpone's household) and those who play the fool by choice (such as Mosca). These deformed creatures reminded even kings that they were mortal. The nobility possessed certain human qualities in common with fools. If too much emphasis is placed on the pleasures of the "belly and the groin," or on flattery and trickery, we ironically diminish our humanity.
The soliloquy is an important theatrical device. It enabled the playwright to comment on the action of the play as well as to reveal the inner thoughts and feelings of the speaker. In this case, Jonson employs it as a quiet interlude before the plot begins to hurdle out of the characters' control to a final comic conclusion. Up to this point, as Mosca's attitude suggests, the villains are the complete masters of events. Things are about to get out of hand.