This explains it. (Or maybe not.)
John Donne's, "The Flea," is a persuasive poem in which the speaker is attempting to establish a sexual union with his significant other. However, based on the woman's rejection, the speaker twists his argument, making that which he requests seem insignificant. John Donne brings out and shapes this meaning through his collaborative use of conceit, rhythm, and rhyme scheme. In the beginning, Donne uses the flea as a conceit, to represent a sexual union with his significant other. For instance, in the first stanza a flea bites the speaker and woman. He responds to this incident by saying, "And in this flea our bloods mingled be."
He is suggesting that they are united in this flea and ,thus, would equally be united in intimacy. In addition, he states, "This flea is you and I, and this our marriage bed, and marriage temple is." The speaker is suggesting that through the flea the two are married. Again, the flea represents marriage, union, and consummation through intimacy. However, the woman crushes the flea, thus, refusing his request, and states that neither she nor he is weakened by its death.
Based on her reaction, the speaker states, "Tis true...Just so much honor, when they yield'st to me, Will waste, as this flea's death took life from thee." In other words, he twists his argument to make the point that the woman will lose as much giving herself to him as she lost killing the flea - NOTHING! Secondly, Donne's use of rhythm aids in shaping the poem's meaning. The poem has alternating lines of iambic tetrameter and pentameter. However, Donne varies this rhythm to create emphasis on particular words or phrases. For instance, in the first stanza he states, "Mark but this flea, and mark in this." Instead of beginning with an unstressed word or syllable as in iambic, Donne stresses the word "Mark." This is important in accentuating his argument. In this same phrase, he uses a pyrrhic foot over "but" and "this" so stress can be placed over the word "flea." Again, the flea is an important part of the speaker's argument and emphasis is placed accordingly.
Finally, Donne's rhyme scheme plays an important part in the meaning. All twenty-seven lines of the poem follow the aabbccddd rhyme scheme. This consistency in pattern reflects the speaker's persistence as he proceeds with his request for intimacy throughout the poem.