Einar Perman, MD, PhD
Stockholm, Sweden

Carl Linnaeus, the famous botanist and father of modern plant nomenclature, was also a physician. Born in 1707 in a rural village in Southern Sweden, he had developed at an early age an interest in flowers and plants. His father was a priest and would have liked his son to also join the church. But Linnaeus had little interest in theology and managed to persuade his parents that he was "too dumb to become a priest.” They agreed that he could study medicine, where his botanical interests would be useful. In his time most medicines came from plants.

After graduating in medicine from Uppsala University in 1731, Linnaeus supported himself as a practicing physician in Stockholm but also held a position in Uppsala as lecturer in botany. In 1735 he went abroad. He stayed mainly in Holland, where in the same year he published his seminal Systema Naturae, taxonomy of plants, animals, and minerals. Plants were its most important part. Linnaeus had a passion for order and classification and organized them into order, genus, and species. Each plant was given two names: first the name of the genus, then that of the species (thus cowslip was Primula Veris). He said it was like "putting a clapper inside a bell.” Soon Systema Naturae became famous among contemporary botanists and came to the attention of George Clifford III, a wealthy man with a botanical garden on his estate at Heemstede in Holland. Clifford offered Linnaeus the position of superintendent of his garden—and also that of his personal physician. He accepted, and stayed at Clifford´s estate from 1735 to 1738. During this time he published several important botanical books, including Hortus Cliffordianus, a catalogue of his hosts botanical garden.

In 1738 Linnaeus returned to Sweden. At first he again supported himself as a practicing physician in Stockholm.1 In 1741 his fortunes improved when he was appointed Professor of Practical Medicine and Natural History at Uppsala University. There Professor Nils Rosén already held the chair in Botany and Theoretical Medicine. At first the relation between the two men was strained, but in 1741, with the consent of the chancellor, Linnaeus was able to change places with Rosén and thus became responsible for Botany and Theoretical Medicine. He moved to Uppsala in the same year and remained there for the rest of his life. Switching professorships was a good move for both men and they became friends. Linnaeus could concentrate on botany, Rosén on medicine. The latter also had a distinguished career, appointed in 1743 as Physician to the King, lecturing to medical students, practicing medicine, and publishing the first major Swedish anatomical textbook. In 1764 he published a textbook on children’s diseases that became famous and was translated into many languages. He is regarded as the father of Swedish medicine and the father of modern pediatrics.

Linnaeus was appointed Chancellor of Uppsala University in 1750 and his fame continued to grow. He revised and expanded Systema Naturae several times, and published Species Plantarum in 1753. This book marks the beginning of modern botanical nomenclature. Many of his best students were encouraged to travel abroad, to America, Africa, China, and Japan, to collect and describe plants. He was praised by Goethe, Rousseau, Strindberg, and others. In 1761 he was ennobled by the King and took the name Carl von Linné. When his health deteriorated, Rosen (in 1762 ennobled as Rosén von Rosenstein) was his physician. Linnaeus died in 1778.

Linnaeus had limited experience with practical medicine. After moving back to Sweden in 1738 he supported himself for a few years as practicing physician in Stockholm, but did not practice after moving to Uppsala in 1741.1 He lectured to students on theoretical medical subjects until 1770. Drawing on his extensive knowledge of plants, he published Materia Medica in 1749. In it he describes 355 plant remedies, which were considered useful in 300 diseases. Genera Morborum, taxonomy of diseases, appeared in book form in 1763 and was followed in 1766 by Clavis Medicinae, which tries to explain the nature of diseases and how they could be cured. It had little impact on contemporary medicine. In his autobiography Linnaeus says that “...it takes a life-time to understand, even by the most learned…”

Our knowledge about his taxonomy of disease comes from lecture notes taken by his students. Comprehensive notes made by Pehr Osbeck during 1746-1747 have recently been found, translated from Latin and made the subject of a book by Uddenberg.1

Linnaeus built his taxonomy on symptoms and manifestations, not on speculative ideas about causes of diseases. With Systema Natura as model he tried to establish a taxonomy of all diseases built only on their manifestations and symptoms. Causes were mostly unknown at the time. Since many diseases have similar symptoms and manifestations (fever, nausea, weight loss, etc.), his taxonomy had little practical value. It was much more difficult to classify diseases than to classify plants and animals.

Linnaeus divided mental diseases into three orders:

  • Disturbances of reason (judiciales)
  • Disturbances of perception (imaginarii)
  • Disturbances of emotion (voluntarii)

In each order he then listed symptoms and manifestations:

  • Under judiciales, five manifestations: Dementia, Mania, Vesani (madness without melancholia, aggressiveness or fever), Delirium, Melancholia
  • Under imaginarii, six manifestations: Hypochondriasis, Vertigo, Syrigmus (tinnitus, imagined sounds), Phantasma (hallucinations), Panphobia, Somnambulismus
  • Under voluntarii, eleven manifestations: Eromania, Theligonia (hypersexuality), Gnostalgia, Rabies, Hydrophobia, Sitta (eating other things than food), Bulimus, Dipsia, Tarantismnus (involuntary dancing movements), Cacositia (aversion against food), Antipathia (general aversion)

With Systema Naturae as model he then named each disease by combining two or more symptoms and manifestations, for instance: Anorexia febrilis (loss of appetite because of fever), Delirium a calculo nephritico (delirium caused by kidney stone), Gnosaologia senilis (intense homesickness in old persons), Phantasma a duplicatis objectis (double vision).

Today we use a modern classification of mental diseases: the DSM-5 (Diagnostic and Statistical Manual of Mental Disorders). It is published in the U.S. and provides a common language and standard criteria for such a classification. It is used in many countries by clinicians, researchers, psychiatric drug regulation agencies, and many others. How does Linnaeus classification compare to DSM-5? Not well. Linnaeus’s description of a symptom or manifestation was sometimes very good (notably melancholia), but as a whole his taxonomy was not useful in practical medicine. It was never published in book form, which probably means that Linnaeus himself was not satisfied with it. Now it has value only for historians studying the 18th century.

Linnaeus deserves credit for his attempt to develop taxonomy of disease. His intention to use only ”what we can see and hear” reflects his background as a natural scientist. The church did not always appreciate this approach, but he was a religious man who believed in God. He seems, however, to have often regarded God as a senior collaborator and mentor. For instance, he is known to have said, “God creates, Linnaeus organizes.” He called his best students his “Apostles.” In autobiographical notes3 he wrote, "God has let me peer into his secret chambers and . . . given me insights into natural sciences larger than anyone else’s. He gave many other examples of what God had done for him and was not a modest man. His contributions were not exclusively in botany. He had a broad knowledge of the natural sciences4 and maintained that man should be studied within this framework. Considering his many important contributions to natural science he is worth much praise. His memory is kept alive in Sweden in many ways: parks, streets, schools, statues, even a Linné University (though not in Uppsala). At present we see his portrait on the Swedish 100 kronor bills.



1. Landell, Nils-Erik. Läkaren Linné. Stockholm. Carlsson Bokförlag (2004)
2. Uddenberg, Nils. Linné och mentalsjukdomarna. Stockholm. Atlantis (2012)
3. Afzelius, Adam. Egenhändiga anteckningar af Carl Linnaeus om sig sielf. Stockholm (1823)
4. Blunt, Wilfrid. The Compleat Naturalist, a Life of Linnaeus. London. Collins (1971)


Since writing this note I discovered that in 1902 Ludvig Hektoen, after whom this Journal is named, lectured to the Scandinavian Medical Society of Chicago on “Linnaeus as a physician.” The lecture was later published as a book. It is informative and well written, acknowledging that “among physician-scientists who achieved their greatest renown in some department of learning other than medicine Carl von Linné, better known as Carolus Linnaeus, must be placed in the front rank.”

Hektoen describes how when Linnaeus showed a distaste for taking holy ordes, his parents thought he should become a taylor or shoemaker, but that indeed he studied medicine in Uppsala—this at a time when the medical faculty of that famous University consisted of only two professors and one adjunct. Linnaeus lectured in botany, but went abroad in 1735 after “intrigues was started against him and his docentship was taken away.” Hektoen reports that Linnaeus spent time in the Netherlands, but does not mention that he published there his seminal Systema Naturae. But his stay in the Netherlands was successful in that he worked with some of the great physicians of the time, notably Boerhaave, with whom he became a great favorite, Haller, and Van Swieten. After his return to Sweden he attempted to build a private practice that grew slowly at first, but then he achieved success in treating gonorrhea and syphilis, became a naval physician, and obtained permission to do autopsies.

But it was after his appointment as professor at Uppsala that Linnaeus achieved his greatest success, gathering about him many students and listeners, carrying out a correspondence with the greats of Europe, and striving to develop the practice of medicine and medical education on a rational basis. He worked on alcohol, diet, fevers, rashes, scurvy, infections, worms, and veterinary medicine, attempted to classify the diseases as understood at that time, emphasized the importance of the pulse in diagnosis, distinguished between various kinds of stroke, and even suggested that fibrinous polyps in the blood vessels may become dislodged and cause “suffocation,” meaning embolization. He thought that fresh air, exercise, sleep, food, and excretions were requisites for a “natural” life. He attracted many foreign students. Among these, Adam Kuhn of Philadelphia spent two years with Linnaeus in Uppsala and later became a prominent member of the University of Pennsylvania.

Why would Hektoen, a medical doctor, have been interested in the Father of Botany? It seems that during his travels in Europe (1895 – 1900) he studied in Uppsala and must have learned a lot about him. He clearly was impressed, because in his lecture he concludes that Linnaeus “is fully entitled to a place among the founders of the scientific school of medicine whose object is to understand the nature of disease and to find and remove the causes of disease.”


EINAR PERMAN, MD, PhD is a retired physician living in Stockholm, Sweden. He is a member of our international editorial board.