John Donne's The Flea:

In this poem, Donne refers to the theme of blood in regards to lust and sin. The flea seems to be a representation of consummation in some way, as Donne explains that "our two bloods mingled be" as a result of the flea "[him... sucking] first, and now sucks thee" (Donne 4, 3). While he acknowledges that this is not "a sin, or shame, or loss of maidenhood," Donne still maintains that it represents sin through the form of gluttony, since the flea is "pampered", or overfed, "[swelling] with the one blood made of two;" (Donne 6, 9). "This, alas, is more than [they] would do," Donne says, implying that he would like to consummate with whomever the poem is addressed to (Donne 9). In this way, Donne links the flea to sins of the flesh, both gluttony, in the flea itself being full with blood, and also lust; while an actual sex act hasn't occured, Donne admits that this is close to it, and that he does lust for one to actually occur.

The theme is continued when Donne states that "This flea is you and I, and this / Our marriage bed and marriage temple is" (Donne 12-13). The flea itself represents the joining of the two in that it contains within itself the blood of both Donne and his would-be lover. Donne decribes that "self-murder" of the flea would represent "sacrilege, three sins in killing three;" in otherwords, the flea contains three "lives": that of Donne (or the poem's speaker), that of the person (assmumingly woman) being addressed, and that of their union and consummation as one (Donne 17-18).

Finally, Donne describes the flea as "guilty" only "in that drop which it sucked from thee" (Donne 21-22). Although both the poem's speaker and his love are missing blood, neither are "the weaker now" (Donne 24). Donne seems to be implying that the woman to which this poem is addressed has some fear of this consummation, but he wants to prove that it will not weaken either of the two, and her worries are indeed "false fears" (Donne 25).