Jan Jesenius

Jan Jesenius
D(ominus) Iohan(nes) Iessenius a Iessen olim Vitenberg, nunc Carolinae Prag(ae) Acad(emiae) rector purpuratus. A contemporary copperplate by Matthäus Merian, 1617
Born	December 27, 1566 Breslau
Died	June 21, 1621 (aged 54) Prague
Doctoral advisor	Hieronymus Fabricius
Doctoral students	Daniel Sennert

Jan Jesenius (also written as Jessenius, German: Johannes Jessenius, Hungarian: Jeszenszky János, Slovak: Ján Jesenský; December 27, 1566 – June 21, 1621) was a Bohemian physician, politician and philosopher.

He was from an old noble family, the House of Jeszenszky, originally from the Kingdom of Hungary. He presented himself in his own works as eques Ungarus ('Hungarian knight'). According to publications, he had Slovak,Polish or German roots. His father, Boldizsár Jeszenszky de Nagyjeszen, left Turóc County (today the Turiec region in Slovakia) because of the Ottomans' military campaign against Upper Hungary and settled down in Silesia in 1555. He married Marta Schülerin, who came from a wealthy German bourgeois family.

Jesenius was born in Breslau (Wrocław), where he studied at the Elisabeth gymnasium. From 1583 he studied at the University of Wittenberg, from 1585 at the University of Leipzig, and from 1588 at the University of Padua.

From 1593 Jesenius was the physician of the Prince of Saxony, and from 1594 professor of anatomy at the University of Wittenberg. After 1600 he settled down in Prague as professor and anatomical consultant for Rudolf II, King of Bohemia and Holy Roman Emperor; in 1617 he was elected rector of Charles University of Prague.