Denying or rationalizing the mythical monstrous hybrids in Aristotle, Palaephatus and Galen is also making use of the animal as a keystone for the construction of human. In such sense, through the reflection on centaurs and monsters, the three authors build the sphere of human as tendentially separated from animal’s. This sphere also tends to include the woman seen as a “dimensional door to theriomorfic alterity”, then as a threat to identity