In the Bibliothèque Nationale in Paris, one of the old maniscripts in French is a version of “Roman de Tristan” . Tristan and Iseult is a legend made popular during the 12th century through French medieval poetry, and inspired from archetypal Celtic legends. It has become an influential romance and tragedy, retold in numerous sources with as many variations. The tragic story is of the adulterous love between the Cornish knight Tristan (Tristram) and the Irish princess Iseult (Isolde, Yseult, etc.). The narrative predates and most likely influenced the Arthurian romance of Lancelot and Guinevere, and has had a substantial impact on Western art, the idea of romantic love and literature since it first appeared in the 12th century. While the details of the story differ from one author to another, the overall plot structure remains much the same. 
On folio 176v, the upper marginalia are interesting in the context of this blog. Another variation on the theme ‘knight v. snail’ may be seen, in which at left a knight stands at rest with his lance and shield. At right a snail and bird are seen; in the middle a lion that is turned towards the knight, but is looking at the snail. The stylised snail has a sinistral shell with many whorls, seemingly in one plane. The animal has two (upper) tentacles, an eye-spot and two structures which either may be interpreted as touted lips or as the lower tentacles. It looks as if the snail is talking to the knight, with the lion listening with attention.
 BNF Ms. Français 776, 291 ff. http://gallica.bnf.fr/ark:/12148/btv1b6000110d.
 http://en.wikipedia.org/wiki/Tristan_and_Iseult (28.iii.2014).