Trilogy

Trilogy, the name given by the Greeks to a group of three tragedies, either connected by a common subject, or each representing a distinct story. A satyric drama was customarily added as a termination, whence the whole was sometimes termed a tetralogy. We possess only one perfect specimen of the classic trilogy—the Oresteia of Æschylus (q.v.), which embraces the Agamemnon, the Chæphoræ, and the Eumenides. Schiller's Wallenstein is a trilogy, and so are Swinburne's Chastelard, Bothwell, and Mary Stuart.