How we cite our quotes: (Act.Scene.Line)
Quote #7
For this bleak existence
Man is never sharp enough.
Hence his weak resistance
To its tricks and bluff. (2.7.182-185)
See the ABAB rhyme scheme? That fun, sing-song quality contrasts pretty starkly with the serious and un-fun message of the song. The lamentation, that humankind is not made for the ugly world we're born into, would be more expected in a slow dirge. The unexpected contrast makes audiences sit up and take notice.
Quote #8
Since this is opera, not life, you'll see Justice give way before humanity. (3.337-338)
Let's unpack these little, snarky lines. The characters are singing about how, because they're in an opera, justice will be served. That means that, in real life, justice doesn't win out—humanity does. And if humanity is in opposition to justice, and usually wins in life, that means things are really unfair in the human world.
Quote #9
MRS. PEACHUM. So it all turned out nicely in the end. How nice and easy everything would be if you could always reckon with saviours on horseback. (3.9.360-362)
The snarkfest continues. Mrs. Peachum is commenting on the deus ex machina, the horseman who comes in at the last minute to save the day, sort of winking at the audience to saying that, obviously, the play is not reflecting real life. Such luck never happens there.