ABSTRACT
In 1618, in Breda (the Netherlands) a momentous encounter took place. Isaac Beeckman, then thirty years old, was a candle-maker, graduated theologian, and spare-time philosopher of nature. He lived in Middelburg but had come to Breda for courtship. René Descartes, twenty-two years old, was in garrison there as a soldier in the army of Prince Maurits. When the two met, they congratulated each other on their rare, shared capacity to “join physics with mathematics”, an activity they then pursued together for several months. 122 They did not attach quite the same meaning to the expression, however. For the young Descartes it referred as yet to the ‘mixed mathematics’ in which he had been raised at the Jesuit college of La Flèche. For Beeckman the expression stood for something new, something that he had already been working on for almost a decade. At the time of their encounter, he was far advanced in his ongoing construction of a natural philosophy (‘physics’) of a novel and on occasion somewhat quantitative kind. He enriched the atomist doctrine with something decisively new: a conception of motion retained. Ancient atomism had postulated the existence of particles that moved through the void in ways left almost wholly unspecified. With Beeckman the way these assumed particles actually move became far more specific. For instance, Demokritos and Epikouros had explained sound in general by invoking the emission, by some source, of sound particles, which on arrival at the ear produce the sensation of sound. Beeckman now explained consonant sound by invoking the emission, by the vibrating string, of sound particles of specifically different sizes and speeds that, once arrived at the ear, produce the sensation of consonant sound.
