Leon Theremin playing his namesake instrument.

From a 1967 New York Times interview with Theremin: “He ushered the visitor into a room in which a small dance floor had been constructed. Mr. Theremin stood on the floor, raised his arms, made motions, and started to play the Massenet Elegy on nothing at all.

The room was filled with sound, and it was positively spooky. No wires, no gadgets, nothing visible. Merely electromagnetic sorcery,

‘I made my last public appearance in 1938,’ Mr. Theremin said. ‘I sometimes think it would be nice to come back once more to United States and show my latest instruments.'”