Progressive Rock, or simply “Prog,” emerged in Britain during the late 1960s from a specific set of musical, social and technological trends. Early Prog Rock drew on many sources, combining elements of Rock and Roll, Psychedelic Rock, Jazz, Folk, and Classical music. What set Prog apart was its grounding in Western symphonic tradition and its reliance on instrumental virtuosity, which had previously been considered the province of Classical and Jazz players and other “legitimate” musicians. There was nothing light or trivial about early Prog, which demanded to be taken seriously as an art form worthy of the same respect accorded to Classical music and Jazz.
Reflecting the influence of Western Classical music, Prog albums — and sometimes even songs, such as Yes’s “Starship Trooper” (1971) — were divided into sections or movements (I. “Life Seeker”; II. “Disillusion”; III. “Würm”). A single Prog track might last 12 or 15 minutes – a far cry from the three-minute song that had long been the Pop music industry standard. Yet at the same time that it mined Classical influences, Prog drew on the 1960s counterculture and its rejection of mainstream values and explorations of alternative conceptions of identity and time.
Progressive Rock was made possible by several important technological and artistic developments. The introduction of the 33 1/3 rpm “Long Play” (LP) record in 1948 allowed for up to 30 minutes of music on each side, considerably more than the 3-5 minutes a 78 rpm disc could hold. The change enabled classical musicians to record an entire symphony on a single record. As the 60s progressed, advancements were made that culminated in growing use of multitrack recording as well as a less complex editing process. Beginning with the Beatles’ watershed 1967 album Sgt. Pepper’s Lonely Hearts Club Band, many Rock bands began to conceive of albums as extended, conceptual, interconnected works rather than collections of disconnected songs.
At the same time, the rise of free-form FM radio in the United States and related programming styles in the United Kingdom allowed disc jockeys broad latitude to explore and play longer-form Rock music. In turn, advances in instrument technology, such as the invention of the Moog synthesizer, allowed for increased musical experimentation. Both would figure into the rise of Prog Rock.