Abstract
The monstrous power of the blind in Diderot’s 1949 Letter is not due to its ability to make people laugh or afraid, as its most common etymology would indicate: monstrum, monstrare, to point to an abnormal fact. The monstrous power of Diderot’s monster is that of one who shows: monere, monitor, in the manner of a guide or pathfinder. It shows us that everything that lives, and especially the human being, is a hybrid. It takes the idea of a possible mixture of animals and humans into account, thus the boldness of an ‘anti-speciesism’ as presented in the fantastical bestiary of Alembert’s Dream. It brings the humanism of essence to an end and invites us to redefine a new social bond.