Jonston was born in
Szamotuły, the son of Simon Johnston, who had emigrated to the
Polish–Lithuanian Commonwealth from
Scotland. Jonston's early education was sponsored by one of his two paternal uncles who had come to the Commonwealth with his father. From 1611 Jonston attended the school of the
Bohemian Brothers in
Ostroróg, then the
Schoenaichianum in
Bytom, and from 1619 the
gymnasium in
Toruń,
Royal Prussia. As a
Calvinist, he could not attend the
Catholic Jagiellonian University. Consequently, he earned his first degree at the
University of St Andrews (1622–25; M.A., 1623), where he studied
theology,
scholastic philosophy, and
Hebrew. His sponsors included the
Primate of All Scotland,
John Spottiswood. In 1625 Jonston returned to the Polish–Lithuanian Commonwealth. Until 1628 he was a private tutor in the household of the Kurtzbach-Zawadski family in
Leszno, where he was an active member of the
Czech Brethren community. Around 1625-28 he published
Enchiridion historiae naturalis, which in 1657 would be translated into English. In 1628 Jonston traveled to the
Holy Roman Empire (
Wittenberg,
Leipzig,
Frankfurt,
Franeker) to resume his studies. He attended the
University of Cambridge, where he studied
botany and
medicine and the Universities of Frankfurt,
Franeker and
Leiden,
matriculating in 1630. That year he was offered a chair of philosophy at
Deventer but declined it, preferring to return to the Commonwealth to become once again a private tutor. This time he took up a post with
Rafał Leszczyński,
voivode of
Bełz, where he tutored his son,
Bogusław Leszczyński. In 1632 Jonston travelled abroad with Bogusław and several other Commonwealth magnates' sons. Their first stop was in
Franeker (1632), followed by
Leiden and
Amsterdam all, that same year, where Jonston published his
Thaumatographia naturalis. In 1634 they visited
England, returning to Leiden, where Jonston received an M.D. degree; soon afterward he would receive a second M.D. degree (
ad eundem) from Cambridge. That year he also received a
Doctorate from both those universities, for his
dissertation De febribus (On
Fevers). Bogusław, Jonston and the others toured Europe until 1636, returning to Poland upon news of Bogusław's father's death. Jonston returned to Leszno, remaining a Leszczyński retainer, in whose service he had the title of
Archiater et Civitatis Lesnensis Physicus Ordinarius. In Leszno he was employed at the Leszno
gymnasium, where he was a friend of
Comenius, who was another important member of the school's faculty. In 1642 Jonston once again turned down an offer to chair a department abroad (this time, that of medicine at Frankfurt). That same year, his
Idea universae medicinae practicae was published in
Amsterdam (it would be translated into English in 1652). Jonston would turn down further offers from
Heidelberg and Leiden. In 1652 he purchased (or inherited) an estate at Ziebendorf (now
Składowice) near
Legnica. In 1665, following the
Polish-Swedish War (
The Deluge), which worsened public attitudes toward the Commonwealth's Protestants, he retired from Leszno to his newly bought estate. He remained there for the rest of his life. He died at
Legnica around 1675. ==Works==