Ehrenfried Walter von Tschirnhaus (or Tschirnhausen), the German mathematician and physicist, was born in Kieslingswalde, near Görlitz, and became count of Kieslingswalde and Stolzenberg. He studied mathematics at Görlitz and at the University of Leiden, where the Cartesian philosophers Adriaan Heereboord and Arnold Geulincx were teaching. After serving with the Dutch in 1672 during a war with France, Tschirnhaus studied further in Leiden and in Germany, and in 1674 he traveled to London, Paris, Rome, Sicily, and Malta. He met Benedict de Spinoza in Holland, English scientists in London, and he undoubtedly met Cartesian philosophers and scientists such as Jacques Rohault and Pierre-Sylvain Régis in Paris. Tschirnhaus finally settled down in Kieslingswalde. He established several factories for manufacturing glass and for grinding magnifying glasses, and was associated with J. F. Böttger in the development of Meissen porcelain. Tschirnhaus...