dispute concerning whether Beeckman had helped Descartes with some of his mathematical discoveries. In October 1630, Descartes wrote a long and harshly abusive letter, apparently meant to crush Beeckman psychologically, in which he declared himself never to have been influenced by Beeckman. However, and despite a few other such fallings-out, they remained in contact until Beeckman's death in 1637. Work and legacy Beeckman did not publish his ideas, but he had influenced many scientists of his time. Since the beginning of his studies he did keep an extensive journal ("Journaal" in Dutch), from which his brother published posthumous some of his observations in 1644 the treatise Mathematico-physicarum meditationum, quaestionum, solutionum centuria. However, this went basically unnoticed. The scope of Beeckman's ideas did not come to light until the science historian Cornelis de Waard rediscovered the Journaal in 1905, and published it in volumes between 1939 and 1953. Rejecting Aristotle, Beeckman developed, independent of Sebastian Basso, the concept that matter is composed of atoms. Beeckman is mentioned to be one of the first persons describing inertia correctly, however he also assumes that a constant circular velocity is conserved. Beeckman had shown that the fundamental frequency of a vibrating string is proportional to the reciprocal of the length of the string. In the analysis of the functioning of a pump he theorized correctly that air pressure is the cause and not the then popular theory of horror vacui. In his time, he was considered to be one of the most educated men in Europe. For example, he had deeply impressed Mersenne, despite their opposing religious views, as well as Pierre Gassendi, who apparently had been turned by Beeckman to the philosophy of Epicurus (atomism). Gassendi even proclaimed, in a 1629 letter to Peiresc, that Beeckman was the greatest philosopher he had ever met. See also Isaac Newton References Bibliography External links The Correspondence of Isaac Beeckman in EMLO 1588 births 1637 deaths 17th-century Dutch philosophers 17th-century Dutch scientists People from Middelburg, Zeeland Leiden University alumni Dutch Freemasons