"And so ended his affection," said Elizabeth impatiently. "There has been many a one, I fancy, overcome in the same way. I wonder who first discovered the efficacy of poetry in driving away love!"

"I have been used to consider poetry as the food of love," said Darcy.

"Of a fine, stout, healthy love it may. Everything nourishes what is strong already. But if it be only a slight, thin sort of inclination, I am convinced that one good sonnet will starve it entirely away." ch 9

When I first read this passage I thought that Darcy was being uncharacteristically cheeseball. Since then I’ve brushed up on my Shakespeare and realised that Darcy is referencing the following line “If music be the food of love, play on”.

That line is explained on bartleby.com as “The first line of the play Twelfth Night, by William Shakespeare. The speaker is asking for music because he is frustrated in courtship; he wants an overabundance of love so that he may lose his appetite for it.”

So, Darcy has actually answered Elizabeth’s rhetorical question. If Shakespeare did not discover the efficacy of poetry in driving away love, he was certainly aware of it.