This lecture examines fugue, arguably the single most representative musical procedure of the Baroque Era. Fugue is defined as a usually monothematic, polyphonic work in which a theme—or, properly, a subject—is examined, broken down, reassembled, and so on in as many different ways as possible. Drawing on fugues by Johann Sebastian Bach and George Frederick Handel, this lecture introduces and examines the three essential parts of a fugue: the exposition, subject restatements, and episodes. The lecture also seeks to define and distinguish the various tuning systems used up to and during the Baroque Era: just intonation, mean tone, and well-tempered tuning.