"The Flea" is an erotic metaphysical poem (first published posthumously in 1633) by John Donne (1572–1631). The exact date of its composition is unknown, but it is probable that Donne wrote this poem in the 1590s when he was a young law student at Lincoln's Inn, before he became a respected religious figure as Dean of St Paul's Cathedral. The poem uses the conceit of a flea, which has sucked blood from the male speaker and his female lover, to serve as an extended metaphor for the relationship between them. The speaker tries to convince a lady to sleep with him, arguing that if their blood mingling in the flea is innocent, then sexual mingling would also be innocent. His argument hinges on the belief that bodily fluids mix during sexual intercourse.