Petrus Severinus

Written by Danya Majeed

Petrus Severinus is the famous late 16th century Danish Royal Physician who is most remembered for championing the theories of Paracelsian medicine.  In this page, we will explore a few of the personal and intellectual journeys which led him to achieve this honor.

Before Medical School


Ribe (Denmark). View over Ribe from the Cathedral church tower. Wikimedia Commons.

Petrus Severinus was born in 1542 in the small coastal town of Ribe in Denmark, post-Lutheran reformation.  His family was of comfortable means and he was educated at the local Latin school as was customary in this time period.  Here, he learned “to read, speak, sing, and write in Latin”[1] and in the final year he learned Greek.  His school had morning and afternoon church services every day, and a full syllabus of religious studies on Saturdays.

After completing Latin school, Severinus intended to study medicine.  Denmark’s University of Copenhagen would have been the obvious choice, as it did have a medical college.  In addition, the University gave importance to this subject, as not one but two full-time faculty positions were reserved for this college.  This was due partly to the Lutheran reformation, which influenced education in the University and “fostered an atmosphere of Biblical humanism… philosophy and medicine were seen as important aspects of a well-rounded education rather than merely as preparation for professional careers.”[2]

Unfortunately, the University was very poorly funded and inadequately staffed.  In fact, the second of the two medicine faculty position was usually empty because no one wanted to work under such conditions.  Severinus decided instead to study in France, and left to pursue his education there in 1562.  He would have been twenty years old.  After one year, he ran out of money and had to come back home.  He spent a few years studying and teaching at the University of Copenhagen, even continuing to teach during a memorable summer when everyone else left because of the plague.  Then, in 1565, King Frederik II of Denmark offered Severinus a scholarship to study medicine abroad.  He matriculated at the celebrated and prestigious University of Padua in Italy in 1566, at the age of 24.

Here in Italy, Severinus was exposed to the mainstream medical theory of his day, which relied on Aristotelian philosophy and the works of Greek physicians such as Galen and Hippocrates, and Islamicate physicians such as Avicenna.  During these years at Padua, however, a new “revival” of Hippocratic medicine was popular, a novel way of looking back at the Hippocratic corpus.  One of the themes of this revival was to avoid emphasis on theoretical medicine at the expense of clinical practice.  Attending physicians at the University of Padua encouraged attention to patients.[3]  One teaching physician was famous for taking medical students into patients’ homes in order to emphasize the importance of learning presentation of symptoms from experience rather than theory.  This revival suggested that Hippocratic medicine at its core was different from the practice of subsequent generations, and this idea had a lasting impression on young Severinus.

Paracelsian Medicine


Contemporary portrait of Paracelsus. Wikimedia Commons.

Paracelsus was an early 16th century physician famous for being the well-known founder of an alternative medicine tradition which became known as Paracelsianism.

The fundamental concept behind Paracelsus’ approach to medicine was that “Experience and piety, neither of which is attained from the dead words of the scholastic physicians, were the keys to true medicine.”[4]  Paracelsus rejected the “dead” writings of Galen and Avicenna.  They were both pagans according to him (and therefore unable to achieve piety) and too caught up in medical theory (and therefore unwilling to gain experience).  On one occasion, Paracelsus burned Avicenna’s Canon in the St. John’s Day bonfire as an emphatic rejection of Pagan-sourced medicine.  I would like to note that Avicenna was, in fact, Muslim and therefore an ardent monotheist – not pagan at all.

Paracelsus looked to the original writings of Hippocrates with the hope of resurrecting the true ideals in his works, which he felt had been compromised by later physicians such as Galen and Avicenna.  This would have significant resonance for Severinus, as he was already familiar with the idea of a ‘Hippocratic Revival’ as we have mentioned.

Paracelsianism was also exceptional for its use of chemical drugs to cure illness.  The idea that a physician must be well grounded in chemistry was a novel approach.  He is sometimes called the father of toxicology. He prescribed a variety of chemical drugs for various ailments, and several of his medicines worked well.  This helped to fuel his reputation.  Unfortunately, sometimes his medicines also killed people.  He became somewhat infamous in this regard, especially with the controversy surrounding his prescribing of antimony.  “The dose makes the poison” is a famous saying attributed to him.  It is not, perhaps, the kind of motto that I would seek in my personal physician, but this attitude did gain him attention.

“Riddled with linguistic novelties, mysterious doctrines, and self-contradictions, Paracelsus’ tracts appeared to some to be the work of a poorly educated madman.”[5]  And indeed, a general antagonism began to grow around Paracelsian medicine, for three main reasons.  Firstly, Paracelsian medicine was “alternative” in its theories and necessarily undermined the authority of mainstream medical practitioners, and this created tensions with the established physicians.  Secondly, his medicines sported success stories but also spectacular failures, and this created tensions with the public.  Thirdly, these new chemical drugs were in direct competition with Galenic drugs, and this created tensions in the marketplace.

These deterrents did not dim the excitement that Paracelsus’ theories held for Petrus Severinus.  While he was still a medical student at Padua, he was exposed to Paracelsianism and was enamored by it.  Echoing the Hippocratic revival taking place at his University, Severinus felt that Paracelsus was more faithful to the original intentions of Hippocrates.  It was new and yet more authentically old.  It offered exciting new cures.  It aimed to address diseases which had not been cured by the existing medical tradition.

Petrus Severinus became the founder of what we now call Paracelsian Neo-Hippocratism. [6]  In order to consolidate his theories, he wrote the book he is most remembered for, The Ideal of Philosophical Medicine.


Title page of Severinus’ Idea medicinæ philosophicae (1571).

After Medical School

Severinus earned his doctorate in medicine in the year 1570, at the age of 28, and returned to his home country.  This was also the year that he published his famous book on Paracelsian medicine, The Ideal of Philosophical Medicine.  He dedicated this book to King Frederik II – the kindly King who had originally given him the scholarship – in expectation of continued patronage.  The next year, he became the Royal Physician to the King and enjoyed a very influential and prestigious role in Danish academic circles.

Denmark was in the midst of an education revival during this time.  King Frederik had invested in the growth and financial stability of the University of Copenhagen.  Aristocrats emphasized higher education for their sons as part of a well-rounded upbringing.  Even those amongst the upper class who were not in need of a career from a financial perspective still sought to be well educated.  Perhaps the influence of this culture is best exemplified by Tycho Brahe, the famous Danish aristocrat who forwent the leisurely lifestyle of a feudal lord in lieu of establishing the most advanced scientific research institution in that period, Uraniborg on the island of Hven.  As we will see, Brahe and Severinus both shared very similar philosophies.

Tycho Brahe and Severinus

Tycho and Severinus attended the University of Copenhagen together prior to Severinus receiving his scholarship for the University of Padua.  Although Tycho’s studies were focused on astronomy, he had taken general courses in medicine as part of a liberal education.  As such, he also became interested in Paracelsian theories, especially with the idea that cures can be found through chemical drugs.

In 1576, Tycho Brahe was given permission by the same King Frederik to feudal lordship over the small Danish island of Hven.  Here he established Uraniborg, his famous research center.  Uraniborg was an intellectual powerhouse, meant to draw academics and scientists across Europe to one focal point, from which they could collectively explore the universe.  Tycho set up several astronomical instruments to observe the heavens, and he is most well-known for his research and theories in this area, including a novel way of approaching the planetary orbits, known today as the Tychonic system.[7]


Detail of Tycho’s mural quadrant, showing his alchemical laboratory in the basement of Uraniborg.

However, Tycho also had a special alchemical laboratory and extensive botanical gardens, which served a different area of interest.  He believed that the exploration of the natural world was equally conducted in the heavens and on earth.  The understanding of substances on Earth and their manipulation via alchemy, was the “terrestrial astronomy” to his “celestial astronomy.”

To illustrate this philosophy, here is a table which Tycho has designed to link celestial bodies with elements in the earth and with specific anatomical organs in the human body.

Cosmos Elements Anatomy
Sun Gold Heart
Moon Silver Brain
Jupiter Tin Blood
Venus Copper Kidneys
Saturn Lead Spleen
Mars Iron Gallbladder
Mercury Quicksilver Lungs

In Tycho’s alchemical laboratory, he experimental with chemical medicines along the ideas of Paracelsus.  He was quite successful in one of the drugs which he formulated.  It was given the name Species Tychonis Brahie and, in fact, remained in drugstores until the beginning of the twentieth century.[8]


Species Tychonis Brahe.

The connection of Tycho’s “terrestrial astronomy” to medicine was not lost on enterprising students in Denmark, and several medical students came to Uraniborg for the purpose of learning sciences that would be useful to them as physicians.  They then returned to their respective schools of learning, influenced by Tycho’s Paracelsian view of the cosmos and receptive to Severinus’ Paracelsian view of medicine.


The story of Petrus Severinus is one of personal and intellectual perseverance.  He is widely recognized as the most famous Paracelsian physician after Paracelsus himself.  We will end with a taste of his brilliant and burning ideas from his book, The Philosophy of Medicine:

Go, my sons, sell your fields, your houses, your clothes, and your rings.  Burn your books, buy shoes, come to the mountains, investigate the valleys, the wildernesses, the shores of the sea, and the deep hollows of the earth.  Observe the distinctions among the animals, the differences of the plants, the orders of the minerals, and the properties of all things and the ways they come into existence.  Carefully learn the astronomy and terrestrial philosophy of the peasants, and do not be ashamed.  Finally, purchase coals, build furnaces, be vigilant, and tend to your preparations without weariness.  For thus will you come to an understanding of bodies and their properties, and not otherwise.[9]



Christianson, John R., On Tycho’s Island: Tycho Brahe, Science, and Culture in the Sixteenth Century, (UK: Cambridge University Press, 2002)

Grell, Ole Peter. “The reception of Paracelsianism in early modern Lutheran Denmark : from Peter Severinus, the Dane, to Ole Worm.” Medical History 39, (1995): 78-94.

Shackelford, Jole. A Philosophical Path for Paracelsian Medicine: The Ideas, Intellectual Context, and Influence of Petrus Severinus, (UK: Museum Tuscalunum Press, 2004)

Shackelford, Jole. “Tycho Brahe, Laboratory Design, and the Aim of Science” Isis 84-2 (1993): 211 – 230

Shackelford, Jole. Paracelsianism and Patronage in Early Modern Denmark, (Rochester, NY: Boydell Press, 1991) 85 – 109

Shackelford, Jole. “The Chemical Hippocrates: Paracelsian and Hippocratic theory in Petrus Severinus’ medical philosophy” Reinventing Hippocrates: The History of Medicine in Context, (UK: Routledge, 2001) 59 – 88




[1] Jole Shackelford, A Philosophical Path for Paracelsian Medicine: The Ideas, Intellectual Context, and Influence of Petrus Severinus, (UK: Museum Tuscalunum Press, 2004) : 25

[2] Ibid., 26

[3] Ibid., 33

[4] Ibid., 37

[5] Ibid., 37

[6] Jole Shackelford. “The Chemical Hippocrates: Paracelsian and Hippocratic theory in Petrus Severinus’ medical philosophy” Reinventing Hippocrates: The History of Medicine in Context, (UK: Routledge, 2001) : 64

[7] John Christianson., On Tycho’s Island: Tycho Brahe, Science, and Culture in the Sixteenth Century, (UK: Cambridge University Press, 2002) : 123

[8] Shackelford, A Philosophical Path for Paracelsian Medicine”: 71

[9] Shackelford, “The Chemical Hippocrates” : 64