Written in the Stars: A Spotlight on Astrology in Medieval Medicine

Updated: May 16

Photo by Greg Rakozy on Unsplash

Human beings have always looked up at the night sky in fascination, wonder and in search for answers pertaining to the very core of our being. In the medieval world, those looking at the sky for answers included medical practitioners; astrology being a mandatory subject for aspiring doctors up until the end of the 18th century.[1] Though astrology may seem like an odd companion for medicine, it was intricately linked to medicine from all the way back in 2000 BC, forming an important part of diagnosis and treatment for maladies. Many of the greatest minds and scientists of the time not only believed in the healing power of astrology, but personally pushed the narrative in their writings and theories as well.[2]

The essence of astrology’s influence came from the belief that the human body, on a smaller scale imitated the universe.[3] From here arose the practice of melothesia; the association of different parts of the body with zodiacal signs. Early astrological texts listed the body parts and disease correlating to each sign, for example the head was assigned to Aries, throat to Taurus, breast to Cancer, belly to Virgo and so on.[2] In a practice known as planetary melothesia, each of the planets and the sun could also be assigned a disease or body part. Using this knowledge, doctors would cast astrological charts to deduce when the patient first fell ill, which would then help in determining the nature and course of the illness. This convention of astrological charting was so common and widespread that even kings and queens would have their personal royal astrologers.[4]

Beyond diagnosis, astrology dominated even when treating illnesses. Many times medicinal herbs could only be collected on specific nights and remedies administered only according to planetary configurations.[5] If not done during this time, the herbs and treatments would be ineffective. Other treatments like that of bloodletting, the process of withdrawing blood to balance bodily fluids, were also under astrological influence: a 1518 calendar manuscript includes a diagram depicting the major veins that were to be drained according to the phases of the moon or the season of the year.[6] In one peculiar method taught at the University of Bologna, a patient’s urine could be judged astrologically without even seeing it in person![2]

In medieval times astrology thrived because it provided a coherent and comprehensive system of thought for diagnosing and treating illnesses. Eventually however, human nature and the human body proved to be far more complex than could be explained by the discipline. Nowadays, most people would reject the superstitions of astrology, considering it downright absurd, but it’s influence can still be seen in the modern world. One can see it in the way common medical terms originated, for example the word “lunacy”, describing madness, was named so because the disease was thought to be caused due to the influence of “Luna” or the moon.[7] Similarly, the practice of astrological charting can still be seen in the casting of horoscopes, which can be found in any newspaper. A direct relationship between astrology and medicine itself has not fully died out either and perseveres as the modern field of medical astrology, and in other disciplines of holistic medicine.

Despite the minor influences that the field exerts today, astrology has mostly vanished from medical science. Today, we have a completely different way of practicing medicine. Today, we use a more solid, scientific, evidence based system for treating illness. Today, we say that the fault for diseases lies in our genes rather than the stars. So it’s intriguing to see that a system of thought that totally dominated medicine for nearly four milleniums has now been rendered obsolete. In a way, it sheds a light onto the human ability to adopt and persist with ideas so considerably wrong, for so long. It further serves to show just how much medicinal practices can change over time. Perhaps in a few centuries, some of the ways medicine is practiced today will totally have changed too, who knows?


  1. Hare E. H. (1977). Medical astrology and its relation to modern psychiatry. Proceedings of the Royal Society of Medicine, 70(2), 105–110.

  2. Greenbaum D.G. (2015) Astronomy, Astrology, and Medicine. In: Ruggles C. (eds) Handbook of Archaeoastronomy and Ethnoastronomy. Springer, New York, NY

  3. Holleran, A. B. (2014). Medieval Medicine: Astrological and Humoral Medicine: Astrology and Medicine. Retrieved from https://scalar.usc.edu/works/engl-690-project/astrology-and-medicine

  4. Learner, T. (n.d) Royal Astrologers: How Kings and Queens have used astrologers over the years. Retrieved from https://www.sloanmagazine.com/royal-astrologers/

  5. Health. (n.d.). Astrology and Medicine. Retrieved from http://www.faqs.org/health/topics/98/Astrology -and-medicine.html#ixzz0mRdylj3T

  6. Great Britain. Royal Commission on Historical Manuscripts., Falkiner, C. Litton (Caesar Litton)., Ormonde, J. Edward William Theobald Butler., Ormonde, J. Butler., Ormonde, J. Butler., Ball, F. Elrington (Francis Elrington). (190220). Calendar of the manuscripts of the Marquess of Ormonde, K. P.: preserved at Kilkenny castle. London: Printed for H. M. Stationery off., by Mackie & co. ld..7. Fraser, JB. (1921) The Influence of Astronomy on Medicine. Retrieved from http://articles.adsabs.harvard.edu /cgi-bin/nph-iarticle_query?bibcode=1921JRASC..15..244F&db_key=AST&page_ind=0&plate_select=NO&data_type=GIF&type=SCREEN_GIF&classic=YES