In her natural encyclopaedy composed in the 1150s, Hildegard of Bingen († 1179 ) attempts to list the creation, in particular the realities from which the meaning remains hidden to most of the men, as animals which are anomalous, even prodigious, by their size and their strength. The case of the cetus, a marine animal in which we can see the whale or more certainly the killer whale, Orcinus orca, shows that it is necessary to operate a crossing of appearances to reach the signification of certain beings, as the title of the work of the abbess, Liber subtilitatum diversarum naturarum creaturarum, suggests it. Considered as a portentum, even a monster by most of the theologians or naturalists, the cetus contributes nevertheless to the order a...