unities, in drama, the three principles derived by French classicists from Aristotle’s Poetics; they require a play to have a single action represented as occurring in a single place and within the course of a day. These principles were called, respectively, unity of action, unity of place, and unity of time.
These three unities were redefined in 1570 by the Italian humanist Lodovico Castelvetro in his interpretation of Aristotle, and they are usually referred to as “Aristotelian rules” for dramatic structure. Actually, Aristotle’s observations on tragedy are descriptive rather than prescriptive, and he emphasizes only one unity, that of plot, or action.
In the French classical tragedy, the unities were adhered to literally and became the source of endless critical polemics. Disputes arose over such problems as whether a single day meant 12 or 24 hours and whether a single place meant one room or one city. Some believed that the action represented in the play should occupy no more time than that required for the play’s performance—about two hours. In spite of such severe restrictions, the great 17th-century French dramatists Pierre Corneille and Jean Racine, confining the crises of their characters’ lives to a single setting and a brief span of hours, produced a unique form of tragedy that derives its austere power from its singleness of concentration. The prestige of the unities continued to dominate French drama until the Romantic era, when it was destroyed, in an evening of catcalls and violence, with the opening of Victor Hugo’s Romantic tragedy Hernani (1830).
In England, where playwrights often had two or more plots in a play, comedy and tragedy were mixed and the setting switched to “another part of the forest” freely; the unities were esteemed in theory but ignored in practice.