According to the art historian Michael Camille, the traces of direct physical attacks can be seen “in hundreds if not thousands” of “medieval illuminated manuscripts”  (see also ). Specific texts, images, or parts of images were found offensive and destroyed by “the owners, guardians, or users of these books”.
It is believed that images acted more powerfully upon the viewers in the Middle Ages than today. It can be explained by some aspects of “medieval theories of vision itself, which gave an active role to the eye in the process of perception. Vision entailed the eye’s actually taking an imprint of the thing seen” . Medieval scholars have thought that either the eye is sending out rays to see the object or the object is sending rays to the eye. Vision was active, dangerous and “prone to sin”. Pregnant women were not allowed to look at “very disgusting animals” (like apes or monkeys) in the face, because they could give birth to children “similar in appearance”.
It seems interesting that “thirteenth- and fourteenth-century illuminators were not worried about” depicting human genitals. The earlier medieval period, “certainly up to the fourteenth century”, might be described as a time when images of naked human bodies were rife, and “when no danger was seen to exist in explicit representations of bodies” .
It all began to change at the very end of the Middle Ages, “not before the fifteenth century”  (compare ) . The medieval church established a control over public decency. In 1402 Jean Gerson, bishop of Paris, wrote a treatise on the corruption of youth, “which urged the secular and ecclesiastical authorities to introduce laws against the exhibition and sale of obscene pictures”. As a result, “postclassical” pornography was invented “at around the same time”.
Starting from the later Middle Ages, the numerous images of male and female genitals were erased from manuscripts. It continued up to Victorian times, when some collectors of manuscripts took a hand in the process in order “to prevent the penis being seen by wife and children” .
Scenes showing naked female characters were often erased from books. “The majority of excised female figures in medieval manuscripts suggests the work of later male clerics” . There was a solid theoretical background for it. In Gemma Ecclesiastica by Gerald of Wales  one can find a chapter entitled ‘On not staring at women’. A medieval clergyman wrote: “Just as one should avoid the company of women, so too should one avoid staring at them or being stared at by them” . He quoted St. Augustine: “Even if your eyes should fall upon a woman, you must never fix your gaze”.
Michael Camille wrote at the end of his essay : “The fact that male and female genitals are still blocked in television representations of the body makes us heirs to a tradition that began in the later Middle Ages, when those heirs scratching out offensive and dangerous things from the beautifully illuminated books they inherited, or making representation itself the veil that covers rather than reveals, saw the obscene for the first time”.
Image: Adam and Eve by Albrecht Dürer (1471–1528) (From Wikimedia Commons, the free media repository)
1. Michael Camille, Obscenity Under Erasure, in Obscenity: Social Control and Artistic Creation in the European Middle Ages / ed. by Jan M. Ziolkowski, Leiden, Brill, 1998.
2. Art Historian Michael Camille, 1958-2002
3. Vadimage Blog: History of one delusion
4. Gerald of Wales – Wikipedia, the free encyclopedia
5. Suzannah Biernoff, Sight and Embodiment in the Middle Ages, Palgrave Macmillan, 2002