The Correspondence of Johannes Isacius Pontanus (321 letters)

Primary Contributors:

Cultures of Knowledge

Portrait of Pontanus. Engraving, reproduced in Peter Hansen, Illustreret dansk litteraturhistorie, 2 vols (1886), vol. 1, p. 388. (photograph: Cultures of Knowledge)

Johannes Isacius Pontanus (1571–1639)

Born in Helsingør [Elsinore], Denmark, the city to which his Protestant parents had fled from Haarlem in the 1560s, Johannes Isaksen Pontanus (he would have been born at sea on their way to Helsingør, hence his adopted name Pontanus, which means ‘of the sea’) spent most of his childhood years in Amsterdam, where his parents had settled after returning to the Netherlands and where his father Isaach Pietersz worked as agent of the Danish king Frederik II. After attending the renowned Hieronymus School in Utrecht, he matriculated in 1589 at Franeker to study medicine and in 1592 progressed to study philology, medicine, philosophy, and mathematics at Leiden. Pontanus travelled to Italy in 1593 and, upon his return, graduated from Leiden in philosophy; that same year, in Denmark, he became acquainted with the historian Arild Huitfeldt  as well as with Tycho Brahe, with whom he seems to have studied astronomy and chemistry. In 1595–96 in England he met William Camden, who entered a signature into his album amicorum. After two further years of study at Leiden, Pontanus travelled again to Denmark where he assisted Huitfeldt in his work on Danish history. From 1600 he accompanied three Danish students on their peregrinatio academica in Germany, Switzerland, and France and was promoted to doctor of medicine in Basel in 1601.

From 1604 (or possibly from 1606) Pontanus worked as professor of natural philosophy, medicine, and mathematics at the Gymnasium Illustre in Harderwijk, Gelderland. He married Anneken van den Heede (or Herde) with whom he had nine children. In 1618 Pontanus was appointed by Christian IV as Royal Danish historian and was charged with writing a history of Denmark from the earliest times. Around the same date his brother — the painter Pieter Isaacz (1569–1625), who according to Karel van Mander was trained at Amsterdam — also went into the service of the Danish king as a painter and art dealer. Pontanus was appointed historiographer of the States of Gelderland in 1621 but, five years later, he declined the offer to become professor of history and Greek at Groningen on account of his burden of work on Danish history. The year 1631 saw publication of the first volume of his Rerum Danicarum historia, and Historia Gelrica appeared eight years later. Pontanus did not live to see publication of the second volume of his Danish history, which was brought out posthumously in 1740. He died in Harderwijk in 1639.

Partners and Additional Contributors

This calendar, compiled from the metadata provided in P. N. van Doorninck and P. C. Molhuysen’s 1909 catalogue, was collated by EMLO Digital Fellows (many of whom conducted this work whilst training) under the aegis of the Cultures of Knowledge project. Thanks are due in particular to Charlotte Marique, to Lucy Hennings, and to Kat Steiner for their invaluable work, and to Robin Buning for his contribution of additional text for this introductory page.

Key Bibliographic Source(s)

Brieven van en aan Jo. Is. Pontanus 1591–1639, ed. P. N. van Doorninck and P. C. Molhuysen (Haarlem, 1909).


Pontanus’s correspondents include some of the most renown scholars of his time — Justus Lipsius, Hugo de Groot, Petrus Scriverius, Joseph Justus Scaliger, Isaac Casaubon, Gerardus Joannes Vossius, Constantijn Huygens, and Claude de Saumaise. Notable is his correspondence with writers of local histories, including Ubo Emmius (Friesland), Arnoldus Buchelius (Utrecht) and Marcus Zuerius Boxhorn (Breda). Amongst his contacts we find his later rival Johannes Meursius, whom Christian IV, in 1625, appointed professor of history and politics at Sorø. Meursius received the same assignment as Pontanus — namely, to write a history of Denmark — which was published in three volumes in 1630–8.

Despite his medical training and professorship in natural philosophy, medicine, and mathematics, Pontanus’s primary interests were the study of history and philology. This is reflected in his correspondence as well as in his published works. Many of Pontanus’s letters concerned his historiographical work, especially his history of Gelderland. He asked his correspondents to send particular archival records and he informed them about the progress of his work. In this category, we should consider his many letters about specific historical events and the meaning of place names. His suggestions for emendations to Latin classical texts were often discussed, as were newly published editions. Pontanus was interested not only in the works of historiographers, such as Sallust, Suetonius, Tacitus, and Macrobius, but also in the poetry of Catullus and Juvenal. Other topics covered in his correspondence include etymology, books that were to be found at auction, publication of the letters of deceased contemporaries, and religious questions, such as the differences between Calvinists and Lutherans, and the danger posed by the Jesuits. Only with Tycho Brahe did Pontanus discuss astronomy.

Pontanus’s published works show a similar emphasis on history and Latin literature. Besides his histories of Denmark and Gelderland, he published a history of Amsterdam, Rerum et urbis Amstelodamensium Historia, which was put on the Index because of its hostility towards Roman Catholics, and Origines Francicae, about the history of the Franks. His Disceptationes chorographicae de Rheni divortiis atque ostiis eorumque accolis populis of 1614, about the earliest peoples living at the mouths of the river Rhine, resulted in a dispute with the geographer Philipp Clüver. In 1637 the Discussiones historicae appeared, in which he refuted John Selden’s claim of English sovereignty over the seas surrounding Denmark. Pontanus published further multiple editions and studies of Latin authors, three works about the Gelderland city of Nijmegen in Roman times, and Latin poems he had written himself. His publications in the fields of medicine and natural science were limited to academic theses and an edition of Robert Hues’s Tractatus de globis coeliesti et terrestri, eorumque usu.

Further resources

Ioh. Isacio Pontano, Rerum Danicarum historia … (Amsterdam, 1631).

Vita et obitus Johannis Isacii Pontani (Harderwijk, 1640).



Karen Skovgaard-Petersen, Historiography at the Court of Christian IV (1588–1648) (Copenhagen: Museum Tusculanum Press, 2001).

‘Pontanus, Johannes Isaacius (1571–1639)’ (Digitaal Wetenschapshistorisch Centrum/Digital Web Centre for the History of Sciences in the Low Countries, accessed 26 November 2015).

Pontanus, Johannes Isacius of Johan Isaakszoon‘, in Nieuw Nederlandsch Biografisch Woordenboek [NNBW], I, cols 1417–20.

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1 Howard Hotson, Commonplace Learning: Ramism and Its German Ramifications, 1543–1630 (Oxford, 2007), p. 160.