Niels Steensen is famous not only for his scientific discoveries, but also for his spirituality. Born into Lutheran orthodoxy, Steensen converted to Roman Catholicism, became a priest, and in 1988 was beatified by Blessed Pope John Paul II. In Steensen’s life the roles of man of science and man of God dovetail in a very exciting way.

Niels Steensen was raised in a devout Lutheran family which numbered several ministers.  He was educated at the latin school associated with Our Lady’s Church, the cathedral of Copenhagen, a school which saw cultivating piety in its students to be one of its chief objectives. Both his family life were more oriented towards the spiritual than that of the average child.

The Chaos manuscript is our earliest indicator of  Steensen’s spirituality.  In 1657 war broke out between Denmark and Sweden. The Swedish army occupied most of Denmark and besieged the capital Copenhagen from August 1658. Regular study became impossible. Steensen began excerpting those books to which he found access. This collection of excerpts from March – July 1659 he called Chaos. 

As befits a medical student Steensen most often excerpted books about medicine, but he excerpted other material too. One of the early excerpts in the Chaos manuscript is of an edifying book  Joseph, Vice-King of Egypt by the German jesuit Jeremias Drexler. In this book Drexler emphasizes God’s Providence throughout all Joseph’s troubles. From this Niels Steensen learned an unshakeable confidence in God’s Providence. This found its expression in what is called Niels Steensen’s prayer: . . . .You have guided me along roads unknown to me. Lead me now on the path of grace, seeing or blind. The Chaos manuscript is our earliest indicator of  Steensen’s lifelong preference for modesty, moderation, and his great faith in providence

The prayer is also the outcome of Niels Steensen’s experiences in Amsterdam where he went in 1660 for further studies. There he made his first anatomical discovery, the duct leading saliva from the parotid gland to the mouth. This parotid duct is today also knwo as ductus stenonis.  At that time Steensen was a boarder in the house of professor Gerard Blaes.  Steensen showed Blaes his discovery, but the professor scoffed. Disappointed, Steensen went to the University of Leiden for further studies and published his discovery of the parotid duct there. Unbeknownst to him, Blaes was publishing Steensen’s discovery as his own. Blaes claimed priority and accused Steensen of plagiarism. Then as now such deceit on the part of a professor and such an accusation constituted a severe crisis for a young researcher, and he needed all his confidence in God’s Providence to pull him through.

Holland was a Calvinist, but liberal, country where many opinions were allowed, even the new Cartesian philosophy. Niels Steensen was so affected by these currents that he experienced a crisis in faith. His own discoveries helped him to overcome this period of doubts. He did not leave his Lutheran faith nor did he publish anything heretical. On the contrary, from  his very first publication on anatomy, Steensen consistently admired God’s work as Creator. This is what inspired his research. After a return to Copenhagen he went abroad again to Paris, and on to Florence. We know that he discussed Catholicism with a Jesuit in Cologne, and with a Danish Catholic noblewoman in a convent in France.  A Corpus Christi  procession in Livorno made a great impression on him, but more influential perhaps were his conversations with good Catholics friends in Florence, particularly the Lavinia Arnolfini and sister Anna Flavia. Slowly Niels Steensen began to embrace Catholicism.

In 1667 Niels Steensen converted. The same year he accepted an invitation to return to Copenhagen as royal anatomist, but only for the sake of Faith. Discussions about faith with old friends in Holland and disappointments in Copenhagen led  him to return to Florence with the intention of devoting his life to leading others to the Catholic Church.

In 1675 he was ordained a priest. The Duke of Braunschweig in Hannover, himself a convert, asked that Niels Steensen be appointed as Apostolic Vicar for the Catholic diaspora in Northern Germany and Denmark. He was ordained a bishop in Rome in 1677 and moved to Hannover. In 1679 The duke died, and Steensen left Hannover and became auxiliary bishop in Münster. During his years in northern Germany, serving as bishop and priest in Münster, Hamburg and Schwerin Niels Steensen showed exemplary integrity,  self-sacrifice, and service. He generously housed and gave financial help to converts who had been renounced by their familes.  Worn out by work, he succumbed to illness and died on  November 25 1686.

August Ziggelaar S. J., 2012