"Double, double toil and trouble / Fire burn, and cauldron bubble." These lines, cackled by the Weird Sisters in Shakespeare's "Macbeth," are part of the most famous incantation –- or magic spell made of words -– in English literature.
Incantation shares a Latin source with enchant, both of which are related to chant. An incantation, then, summons a thing or action into being with words that are sung, spoken, or written. Long before it became the catchword of stage magicians, abracadabra was regarded as a powerful incantation capable of warding off serious disease. The phrase hocus pocus may be a corruption of a seventeenth-century incantation spoken during the Roman Catholic liturgy of the Eucharist, "hoc est corpus."