Simon Stevin

Simon Stevin was a Flemish mathematician, scientist and music theorist, born in Bruges in 1548 and active in the northern Netherlands, where he died around 1620, probably in The Hague. He had no university education: he first worked as a clerk in a trading house in Antwerp and then as a lower-ranking official in Ghent. By around 1581 he was already living in Leiden, the city where he carried out the most important part of his scientific work, dating from the 1580s, which covered mercantile arithmetic, decimal notation, and statics and hydrostatics treated according to the method of Archimedes.

Around 1593 he entered the personal service of Stadtholder Maurice of Orange as an engineer, and later received the official appointment of Quartermaster General of the army of the States General, a post he already held in 1604. Part of his duties consisted of teaching science to his curious commander. As the quantitative aspects of music theory were then considered part of science, Stevin planned to include a short treatise on music theory in his Hypomnemata mathematica (Leiden, 1605–1608), but, probably because of criticism from the Nijmegen organist Abraham Verheyen, he left it unpublished. The text survives in two manuscripts.

The core of the treatise is his theory of consonance, an approach that is unusual in the history of music theory. Against the Pythagorean discovery that consonant intervals correspond to ratios of simple whole numbers, Stevin argued that only the geometric division of the octave yields the true ratios of the consonances, so that all semitones would naturally be equal. His position, however, now seems closer to equal temperament than to a solid acoustic explanation, and his contemporaries Mersenne and Descartes rejected it without reservation.

His legacy is paradoxical: although his theory of consonance lacks foundation, he anticipated equal temperament, which began to be considered viable around 1630. That reading, however, is retrospective, since his conception of tuning was less sophisticated than it appears; for him, music was above all an exercise in abstract arithmetic.