At the time Mercutio makes his famous "Queen Mab" speech in Shakespeare's Romeo and Juliet, he and Romeo, together with a group of their friends and kinsmen, are on the way to a party given by their family's arch-enemy, Lord Capulet. Their plan is to crash the party so that Romeo may have the opportunity to see his current love, Rosaline, whom they know has been invited to the Capulet's masque that evening.
Romeo, whom his friends seem to consider generally very witty and fun, originally thought the party-crashing would be a wonderful idea, but suddenly is overcome by a sense of great foreboding; although they "mean well in going to this mask . . . 'tis no wit to go" (I, iv, 48-49). This annoys Mercutio, who does not recognize Romeo's reluctance as a genuine premonition, but feels it is simply another example of Romeo's lovesick whims. Romeo tries to explain to Mercutio that it is based upon a very disturbing dream, and Mercutio passes that off as silly, telling him that "Dreamers often lie." Here he is not saying that Romeo himself is a liar, but that people should put no faith in dreams. But Romeo is insistent; dreamers lie "in bed asleep, they do dream things true" (I, iv, 52).
This suddenly launches Mercutio into a speech that alters the entire pace of the scene. Up to now, the conversation has been typical of a group of people walking through the streets-short phrases, a generally relaxed mood. With Mercutio's words, "O, then I see Queen Mab hath been with you!" he plunges into a forty-two line speech which is actually composed of only two sentences, giving him barely enough breath to pause between phrases. The gist of the speech concerns Mab, whom Celtic mythology considered to be the midwife of the fairies, and who also is held to be responsible for human beings' dreams.
The Queen Mab speech is totally fanciful, describing, as if to a child, this tiny little creature who flies through the air in a small carriage, driven by a "wagoner" who is a gnat. On the surface this seems like it should be charming, but when one boils it down, it isn't charming at all. For example, Queen Mab's "cover" of her carriage is made of grasshopper wings, which implies that someone must have pulled the grasshopper's wings off to make it. Ditto for the spider's legs which serve as the wagon's spokes, and the riding-whip which is made of a cricket's bone. Mercutio points out that the entire apparatus is not "half so big as a round little worm / Pricked from the lazy finger of a maid"-but do living maid's fingers have worms in them?
He leaps off the topic of Mab's carriage, however, to describe its route. Mab's function is apparently to drive over the sleeping forms of human beings, and cause them to dream of things appropriate to their station in life. For example, she causes lawyers to dream of fees, ladies of love, and soldiers of warfare. Here, again, this sounds fanciful...