Nature - Andreas Vesalius's illustrations of the human body baffled some early readers, as his marginalia reveal. Dániel Margócsy, Mark Somos, and Stephen N. Joffe explain.

[dropcap]The[/dropcap] " De Humani corporis fabrica" of the Renaissance anatomist Andreas Vesalius Its more than 200 woodcuts revolutionized the way people imagined the human body, skinned and cut open, revealing muscles, nerves, organs, and bones. Even today, 475 years after its first publication, the bold images of "muscular man" in sinuous poses (by illustrator Jan Steven van Calcar) seduce.

More than 700 copies are of the 1543 and 1555 editions overseen by Vesalius. Of these, about two-thirds contain comments in the margins, bizarre scribbles, colored and even defaced images. Early readers, in evidence, diligently studied Vesalius's treatise and yet had no scruples about writing in an extremely expensive volume.

With a deeper look, such annotations and scribblings tell two stories. One is that some people found the images disconcerting and tried to clarify them in novel ways. Another is that the pious found the necessary nakedness of the figures scandalous, and felt impelled to weigh them down with ink and scissors. Our study of the reactions of hundreds of readers has taught us that themedical communities do not always adopt innovative solutions quickly, even when they are presented in such an elegant format as the Factory . it takes time to get used to the novelty. And we learn that even the most ingenious scientific minds can fail to predict how political and religious institutions will respond to their work. The portal vein, with the haemorrhoidal vein highlighted. The portal vein, with the haemorrhoidal vein highlighted. Credit: Dean and members of Queen's College, Oxford.

The first readers of Factory were the first generation of physicians and surgeons in Europe to tackle the daunting task of using detailed printed images to identify the body's organs and learn about human physiology. Vesalius and van Calcar faced challenges of their own. The image of the Factory of the branching of the portal vein, which carries blood from the intestine to the liver, is highly complex - and unsuccessful. It is almost impossible, for example, to detach the hemorrhoidal vein. (At the time, this was important because the vein was thought to be the cause of both menstruation and hemorrhoids, considered analogous processes that purged corrupted blood from the body.)So in a copy now in the library of Queen's College at Oxford University in the UK, someone used a quill and red ink to color this winding vein, like a child playing a game of maze.

In a copy which belonged to the physician Georg Palma (Nuremberg, Germany), an intricate image of the brain is "enhanced." Palma painted six pairs of cranial nerves in different shades in watercolor and used the same colors to underline the corresponding pairs in the text on the next page.

Even Vesalius realized that his images could be confusing and came up with an ingenious method to explain them. A letter or number was printed on the image of each body part, with a separate key. Unfortunately, the letters and symbols were often too small to stand out from the background full of colors and shapes. Some frustrated readers underlined, highlighted, enlarged, orOn a muscular man, for example, the tiny letter identifying a thigh muscle was barely visible, and a confused reader desperately asked if it was the Greek letter µ or the Roman letter u .

Faced with such challenges, many physicians may have given up on imaging. In fact, when we reconstruct what early modern readers and scholars found fascinating about the Factory , it was evident that it was the text. The clear majority of sixteenth- and seventeenth-century readers who annotated the book focused on this and left no trace of having engaged with the illustrations. The sixteenth-century criticism of the Factory confirm this impression, because they tended to discuss only the text.

That's no surprise. The erudite readers of Factory were trained in the traditions of Renaissance humanism, which strongly emphasized textual analysis. Even if they found it difficult to interpret visual information, physicians were experts at understanding long Latin texts. Moreover, the "inner universe" of the body had barely been mapped. Even today, it is difficult to understand images of internal organs if you have never seen a dissected body, andradiologists need years of training to interpret radiographs or MRI scans.

If the images were not useful for understanding the body, what was their purpose? For Church authorities of the period, the answer was clear. They argued that such pictures had an erotic appeal because they showed the genitals-and therefore should be censored. The first version of the Index librorum prohibitorum the list of books banned by the Catholic Church, came out in 1559, and did not mince words about "licentious" books. This included volumes on anatomy. Many who possessed the Factory felt they should paint aprons on the "muscular men" (as in the copy belonging to the Jesuit College of Bourges in France), or cut off the offending parts.

Only a minority of copies of the Factory We checked all surviving copies from the period and found the images intact in most of them belonging to Catholics of the period. The way the censorship happened raises the hypothesis that, at least until the trials of Galileo Galilei in the early seventeenth century, the Church found anatomical illustrations more dangerous than heliocentrism.

*Cover image: A muscle man De humani corporis fabrica Credit: Bibliotecha Civica Romolo Spezioli, Fermo. Identif.: 1e7n.1582

Reference :

1. Dániel Margócsy, Mark Somos, and Stephen N. Joffe. Sex, religion and a towering treatise on anatomy. Nature 560 , 304-305 (2018). doi: 10.1038/d41586-018-05941-0. translated by Victor Hugo Joaquim. available at: < /www.nature.com/articles/d41586-018-05941-0 >