Isaac Beeckman (1588–1637) is chiefly known today because of his association with Descartes, whom he met by chance at Breda in November 1618. In January 1619 Descartes, then aged twenty-two, sent him as a New Year's gift his earliest surviving work, the Compendium musicae. Theirs was a mutual interest in music and musical theory. Here I propose to deal only with Beeckman as a theoretician of music, although we should bear in mind that he had wide-ranging scientific interests. These grew out of his humanist education at the University of Leiden, his technical training in his father's business of candle- and tube-making, his highly individualistic Calvinism, and his own enquiring, independent mind. Except for a few pages in Koyré's Études Galiléennes and a long note by Cornelis de Waard in the Mersenne Correspondance, Beeckman's scientific ideas have been little studied. There is now at least a most useful dissertation on Beeckman in Dutch, but as little as is known about his science still less is his musical theory a subject for scholarly inquiry. This essay may serve as a remedy.

Beeckman was a qualified physician, but spent most of his life as a successful schoolteacher.