Robert Grosseteste, Bishop of Lincoln (face rubbed), in mitre and red cope, with crosier, seated on left speaks to a seated group of five people, mostly women. Tree on right; large bird with long beak at top.

“The margins are full of images of disembodied body parts, plants, animals, even portraits of cross-eyed kings, which relate to the main body of text and act as a mnemonic for the reader,” Greene says. “Even though you open the manuscript knowing it is a medical text designed for practical use, nothing quite prepares you for seeing a disembodied leg, posterior, or penis pointing at salient parts of the text!”

But the fact that so many patrons did not balk at the expense implies that many people considered these ridiculous monstrosities to be desirable, even valuable.  In the last 30 years or so, significant efforts have been made to understand marginalia in its proper context; there are many theories about its function and purpose (see for example Lillian Randall's Images in the Margins of Gothic Manuscripts or Michael Camille's Image on the Edge: The Margins of Medieval Art).

Criticism of these kinds of images is nearly as old as the images themselves.  The most famous (and freqently cited) is that of Bernard of Clairvaux, who asked: 'What excuse can there be for these ridiculous monstrosities...? One could spend the whole day gazing fascinated at these things, one by one, instead of meditating on the law of God. Good Lord, even if the foolishness of it all occasion no shame, at least one might balk at the expense.' (Bernard of Clairvaux, Excerpts from the Apologia to Abbot William of St-Thierry, VII.30; see here for more). 

side from hunting scenes, one may broadly divide ancient depictions of hares into two iconographical groups. In the first group, the hare embodies the love of a man for a woman. On numerous Greek vases, for example, we see a depiction of Eros, the God of Love, with his two symbols, the lyre and the hare; other scenes show Eros pursuing a hare as a symbol of love, which, as we know from Book 1 of Philostrates’ Imagines, has been given a special gift: fertility.