At the very start of the play, in Act 1, Scene 1, two servants (Fag and the Coachman) have a conversation in which one of them uses a simile:
Fag: You’ll be secret, Thomas?
Coachman: As a coach-horse.
In the quote above, the Coachman compares the secret Fag is about to share with him to a "coach-horse." Doing so introduces one of the main themes of the play: deception and secrecy, and, more subtly, their inevitable end. It is notable that the figurative language the Coachman uses to relay his trustworthiness and secret-keeping capability directly relates to his profession.
Sheridan’s choice to write the Coachman’s dialogue in this manner is funny, but it also serves as commentary on the lower class’s limited creativity to think beyond their station. While in later scenes in the play Fag and other characters demonstrate their desire to appear more educated and refined through unsuccessful attempts at appropriating the language and turns of phrase belonging to the upper classes, with this simile, Sheridan also turns his satirical eye towards those for whom progress has yet to make a marked difference in their lives.
Furthermore, the fact that a coach-horse is very large and thus difficult to hide or disguise adds a layer of irony to this simile and also hints at the fact that secrets can never stay secret for very long. Thus, this simile also foreshadows the fact that all deception in the play will eventually be revealed.
In Act 3, Scene 4, Acres makes a simile comparing cotillion dancing to algebra, thus revealing his lack of sophistication and gentlemanly refinement:
Sink, slide – coupee – confound the first inventors of cotillons! say I – they are as bad as algebra to us country gentlemen – I can walk a minuet easy enough when I’m forced! – and I have been accounted a good stick in a country dance. Odds jigs and tabors! I never valued your cross over to couple – figure in – right and left – and I’d foot it with e’er a captain in the county! – but these outlandish heathen allemandes and cotillons are quite beyond me! – I shall never prosper at ’em, that’s sure.
The quote above demonstrates that Acres lacks some of the fundamental skills considered necessary to all men belonging to his class in Sheridan’s time. He has not mastered the art of dance, which men would have been expected to know very well, as the practice of proper dancing was crucial to courtship and the functioning of society more broadly. Comparing dance to mathematics (when it comes to difficulty) hilariously shows his unsuitability for courtship, as well as his unsuitability to manage finance or property—qualities most unbecoming in a man of his station.
