Born in 1597, the son of a Leiden professor of medicine, Vorstius (Voorst) studied humanities at Leiden University before embarking on a European tour ending in Padua, where he obtained a degree in medicine. In 1625 he succeeded his father as professor of medicine and director of the botanical garden at Leiden. In that capacity he published catalogs of the plants growing in the botanical garden (1633) as well as an edition of the Aphorisms of Hippocrates (1628). Never a very active scholar, he was often reprimanded by the university administration for neglecting his classes. No more than one letter of Descartes to Vorstius survives. It contains a full exposé of Descartes’ theory of animal spirits (June 19, 1643; AT III 686–89). There must have been personal meetings as well; in a letter to De Wilhem, Descartes refers to a dinner party he attended at Vorstius's house (May 24, 1647; AT V 33). Moreover, Descartes’ letter shows that Vorstius also took the former's defense, probably in the assembly of Leiden professors. Vorstius left hardly any writings, so it remains unknown whether he was sympathetic to Descartes’ medical and physiological ideas.

See also Animal Spirits, Medicine