Leonardo da Vinci’s viola organista was a keyboard instrument designed to sound strings by rubbing them with a continuously moving bow. He developed versions of the idea in manuscripts from the 1470s onward.
Pressing a key selected a string, while rotating mechanisms moved a bowing surface against it. This sought to combine the expressive sustained sound of bowed instruments with the control of a keyboard. Leonardo drew several versions, but no surviving original instrument is known.
The viola organista is not a conventional viola and does not use the plucking mechanism of a harpsichord. Modern instrument makers have built reconstructions based on Leonardo’s drawings, demonstrating that the concept can produce sound, though historical details remain debated.