Ehrenfried Walther von Tschirnhaus

Ehrenfried Walther von Tschirnhaus (1651-1708) was a German mathematician, physicist, physician and philosopher of the seventeenth century, active in the Electorate of Saxony. He is remembered for combining mathematical precision with a view of knowledge that anticipated some Enlightenment ideas, and for his direct contact with several leading minds of his age.

He was educated at the Gymnasium in Görlitz and then studied mathematics, philosophy and medicine at Leiden. He travelled through France, Italy and Switzerland, served in the Dutch army between 1672 and 1673, and met Spinoza and Huygens in the Netherlands, Newton in England and Leibniz in Paris, with whom he corresponded for the rest of his life. He became a member of the Académie Royale des Sciences in Paris.

His mathematical work includes the theory of catacaustics by reflection, which he developed in 1682 and showed to be rectifiable, determining the envelope of a moving curve, a rare achievement at the time. In 1683 he published in Acta Eruditorum the transformation that bears his name, which removes certain intermediate terms from an algebraic equation. He is also associated with the Tschirnhausen cubic. In 1696 he was one of the few mathematicians to submit a solution to Johann Bernoulli's brachistochrone problem. He also made lenses and mirrors. In Medicina mentis (1687) he combined deductive method with empiricism, a philosophy that shows links to the Enlightenment. For many years he was overlooked as a philosopher, and he is now studied mainly in relation to Spinoza and Leibniz.

Back in Saxony, he carried out systematic experiments with mixtures of silicates and earths at different temperatures in order to make porcelain, then available in Europe only as a costly import from China and Japan. He proposed a factory to Augustus II, but was refused. His sudden death in 1708 stopped the project, which resumed in 1709 under Böttger. Contemporary testimonies from people close to the work suggest that the invention was Tschirnhaus's, although Böttger's name remained permanently linked to European porcelain.