Perpetuum mobile

What it means

Perpetuum mobile is Latin and means “perpetual motion.” In music the term designates a piece that runs from beginning to end in evenly continuous, usually fast note values, without rests and without interruption of the movement.

The name alludes to the idea of a machine that moves forever without an input of energy. Musically this impression arises through the unceasing sequence of equal values, which offers the listener no points of rest. Some pieces of this kind are laid out so that the end can pass seamlessly into the beginning and the movement theoretically never stops.

The perpetuum mobile as a genre is to be distinguished from motoric rhythm as a general stylistic device. A perpetuum mobile is usually a virtuoso individual piece, often for violin or piano, that shows the player's technical endurance and evenness.

In the notation

The perpetuum mobile is recognizable by long, uninterrupted sequences of equal note values, usually sixteenths, extending over the whole piece. Rests are almost entirely absent. The designation stands as a title or as a movement heading.

Musical use

Pieces of this kind appear especially in the nineteenth century as virtuoso showpieces. The term, however, is also applied retrospectively to older movements that rest on continuous movement, for instance certain études or preludes. In orchestral music it occasionally appears as a humorous title.

Well-known examples come from Paganini and Johann Strauss. Characteristic are evenly continuous fast note values that create the impression of a never-ending movement. Often the beginning is taken up again at the end, so that the piece could theoretically continue endlessly.

Performance practice

Keep the movement even over the whole length — the greatest difficulty is endurance. Choose a tempo you can hold to the end. Look for points of emphasis within the movement, so as not to fall into mere reeling off. And plan spots for relaxing hand and arm within the movement, since rests are absent.