The Collation

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Balancing information and expertise: vernacular guidance on bloodletting in early modern calendars and almanacs

A guest post by Mary Yearl

The first calendar printed as a book in Europe was also the first to contain a printed image of a bloodletting man.1 This point alone is indicative of the importance bloodletting played in medieval and early modern regimens of health. There were other medical approaches that would have occupied a more central place in every day care (e.g., plant-based remedies and diet), but bloodletting demands attention.2

The first printed image of a bloodletting man in Europe, which appeared in a calendar printed as a block book in 1474. Regiomontanus, Joannes, 1436-1476. Calendarium. [Nuremberg, Sold by Hans Briefftruck? 1474] This copy: Lessing J. Rosenwald Collection, Library of Congress, Incun. 1474 .M82. Available from:
Today, bloodletting captures the imagination in a way that supports negative stereotypes of pre-modern medicine as barbaric. At the time bloodletting guides were written, the attention given to the practice was at once a confirmation of its importance in both preventative and curative medicine and an acknowledgement of its dangers.

Bloodletting was a routine operation, but as with all operations it came with risks. Even when not presented as such, a key purpose of works on bloodletting was to impart knowledge necessary to avoid unfortunate results. The rules to follow do not resemble the sanitary protocols we might follow today, but they do make perfect sense according to the logic that interpreted the human body as a microcosm in constant dialogue with the macrocosm it reflected: the universe. Each of the four humours (blood, yellow bile, black bile, phlegm) corresponded to one of the four elements (air, fire, earth, water), the seasons (spring, summer, autumn, winter), internal organs (heart, gallbladder, spleen, brain), etc. Moreover, the parts of the body from the head to the feet and the signs of the zodiac were also assigned correlations (e.g, with Gemini, Libra, Aquarius corresponding with air, etc.).

In this context, safe bloodletting was dependent upon a larger astrological picture that took into account the phases of the moon in relation to the signs of the zodiac. This included not only what was happening in the skies at a given time, but also an individual’s medical and mental tendencies as determined by what was occurring astrologically when they were born. With so many pieces in play, it is not surprising that popular almanacs often advised patients to consult an expert; for instance, in the English manuscript discussed below, William Mount was careful to advise the reader to consult a “learned & wise phisicion & Astronomer” since “Many circumstances therbe more necessarie to be observed in these matters, then the motion & dominion of the Moone…”.3

Comparison of the zodiac man in an early 15th century manuscript and late 15th century incunabulum. Left: [Encyclopedic manuscript containing allegorical and medical drawings], [South German, 1410], Lessing J. Rosenwald Collection, Library of Congress, available from: Right: Johannes de Ketham Fasciculus medicinae (Venice, 1500), available from: Click to enlarge.
Typically, learned medical works on bloodletting contain elaborate instructions that provide guidance based upon physical and astrological considerations: “vein man” is a visual guide to which veins to open, depending upon the ailment, the seasons, etc. Nonetheless, “vein man” rarely appears alone; “zodiac man” is his usual partner. Though these works were an extension of a tradition of learned Latin medicine, their precision and clarity made them appealing to a literate elite. This fluidity between Latin and vernacular learned texts is evident in the German manuscript whose images are shown here as a point of comparison to Johannes de Ketham’s (fl 15th cent.) popular Fasciculus medicinae, typically described as the first illustrated printed compendium of medicine. Though Ketham’s work was first published in Latin in 1491, it was translated into Italian almost immediately while continuing to be printed in Latin well into the sixteenth century.

Comparison of 15th-century manuscript and early printed depictions of a vein man. Left: [Encyclopedic manuscript containing allegorical and medical drawings], [South German, 1410], Lessing J. Rosenwald Collection, Library of Congress, available from: Right: Johannes de Ketham Fasciculus medicinae (Venice, 1500), available from: Click to enlarge.
What is interesting to consider is how information from decidedly learned texts was transmitted into more popular forms of knowledge. Almanacs and calendars already occupied an important place in the manuscript tradition in the fourteenth century, but with the advent of printing later in the fifteenth century they became cheap and easy to disseminate.4 Many of these were produced as single sheets that included separate calendars for bloodletting and for feast and/or saints’ days. The information conveyed was not only about days, months, and years; in many cases they featured what might be described as a visual synopsis of basic rules for when to bleed.

As mentioned and pictured above, the first printed European calendar was a German block book that is also notable for containing the first printed bloodletting man. The figure has some unusual features: he looks like a zodiac man, but in addition to the signs of the zodiac he has lines pointing from the general location of a vein to a sign of the zodiac so as to reinforce the dangers of bleeding when the moon was moving through the corresponding sign of the zodiac. This man comes pre-identified as “[A]Derlossman” (Aderlaßmann), a designation that continued in later Germanic calendars and almanacs for similar figures that combined elements of a vein man and a zodiac man.

An example of a later work that continues the Aderlaßmann imagery comes from a fragment of an almanac for the year 1496. The Aderlaßmann is prominent: he appears in the center at the bottom of the page and is double the size of the four surrounding health-related scenes. Three of the accompanying images relate to the procedure of bloodletting: one is of a man being scarified and two are of women being bled in the arm (one in the right arm, one in the left). Meanwhile, the didactic value of the Aderlaßmann is increased in this case because each line from vein to astrological sign is marked as to whether or not it is a good time to bleed.

Fragment focused on bloodletting from an almanac for the year 1496. [Calendar for Austria, 1496]. [Nuremberg?]: Kaspar Hochfeder, 1495. Available from: Click to enlarge.
We do not know how much we are missing from the 1496 almanac, but works such as this are often so packed with diverse pieces of information that guidance on bloodletting is limited to the Aderlaßmann figure and a few lines of verse reminding the reader of the image’s significance; this can be seen in the example of an almanac printed in Zürich in 1541.

Nach der Geburt Christi Jesu unsers Seligmachers M.D.XLI. Jar. [Zürich] : getruckt zu Zürich by Augustin Fries zum Wolckenstein uff Dorff, M.D.XLI. [i.e. 1541]. Zentralbibliothek Zürich, Kalender Schweiz 1541 III,1. Available from: Click to enlarge.
The common thread in works addressing bloodletting is that the practice is safe and healthy as long as one follows the rules. The purpose of the bloodletting man is to serve as a visual reminder and reference point for written rules, which tend to be absent from calendars and almanacs.

Not all of the guides for bloodletting followed the usual model. A manuscript written in England in 1583 is worth noting because the section on bloodletting in this much larger work omits the bloodletting man in favour of a table to help determine when to bleed or perform other evacuative remedies. Accompanying the table are detailed instructions that serve as a primer for using an astrological bloodletting calendar. The work was written by William Mount, who was the chaplain to Lord Chancellor of England, Sir Thomas Bromley. Given that Mount dedicated the work to Bromley, one wonders whether he was the intended reader of these precise instructions. We do not know, but the accompanying text provides a clear guide for the modern reader who might wonder how to interpret such a table; for this reason Mount’s explanation is transcribed in full in the Appendix.

The key point to glean from bloodletting calendars and almanacs was to avoid bloodletting when the moon was in the sign of the zodiac governing the part of the body to be bled. Even though lay readers were not going to use the information to bleed themselves, it would help them determine when it was safe—or not—to seek out a bloodletter.

Table used to determine the place of the moon in the twelve signs of the zodiac. William Mount, A shorte declaration of the meaning and use of a perpetuall calendare or almanack, 1583, B.O. 7601, p. 39, Osler Library of the History of Medicine.


Mary Yearl (MLIS, PhD) is the Osler Librarian at the Osler Library of the History of Medicine and an Associate Member of McGill’s Department of Social Studies of Medicine. She wrote her doctoral thesis on the medical and spiritual functions of regular bloodletting in medieval monastic life. As a Folger Institute Fellow in 2020-2021, she has returned to bloodletting as a topic of research and is pursuing a project entitled “Bloodletting in the first 150 years of printing: a window into vernacular medicine.” In her work at the Osler Library, she often engages in lessons about representation in medicine; medical ethics; and subcultures of medical knowledge.

  1. Regiomontanus, Joannes, 1436-1476. Calendarium. [Nuremberg, Sold by Hans Briefftruck? 1474]. This copy: Lessing J. Rosenwald Collection, Library of Congress, Incun. 1474 .M82.
  2. For more information on bloodletting in learned medieval medicine, see: Faith Wallis, ed., Medieval Medicine: A Reader, Readings in Medieval Civilizations and Cultures, XV, (Toronto, Ontario: University of Toronto Press, 2010), pp. 281-288; Linda E Voigts and Michael R McVaugh, “A Latin Technical Phlebotomy and Its Middle English Translation,” Transactions of the American Philosophical Society 74, no. 2 (1984): 1–69. Available from:
  3. William Mount, A shorte declaration of the meaning and use of a perpetuall calendare or almanack, 1583, B.O. 7601, p. 39, Osler Library of the History of Medicine. p.43. The same was seen in other English almanacs: Louise Hill-Curth, English almanacs, astrology and popular medicine, 1550-1700 (Manchester: Manchester University Press, 2018).
  4. On the Germanic calendar tradition, see Francis B. Brévart, “The German Volkskalender of the Fifteenth Century,” Speculum 63, no. 2 (1988): 312–42. Available from: Similar astrological bloodletting information has been documented in Hebrew manuscripts. Justine Isserles, “Bloodletting and Medical Astrology in Hebrew Manuscripts from Medieval Western Europe.” Sudhoffs Archiv 101, no. 1 (2017): 2–41. Available from:

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