The speaker asks his beloved to examine a flea that has bitten them both, implying that through sharing the flea's blood they are now connected. He argues that killing the flea would be akin to suicide or sacrilege. The woman objects that the flea means nothing, but the speaker insists their union in the flea is a type of marriage. He says killing the flea would waste the honor she would gain by yielding to him, twisting her argument to his advantage. The poem uses the flea as a metaphor to persuade the woman to have sex without losing her virginity.