Sometime around 1986, Laurie Spiegel shipped a piece of software for the Mac, Amiga, and Atari ST that had no real category. It wasn't a sequencer. It wasn't a synthesizer editor. It was a musical instrument — one you played with a mouse, in real time, while it quietly kept everything you did harmonically coherent. She called it Music Mouse — An Intelligent Instrument. Now Eventide has brought it back.