Defining the Wilderness implies to start from the christian authors who are authoritative in early Middle Ages. The perception of the wild nature is a synthesis of the antique knowledge and the conception of the universe as presented in the Bible, then developed by the exegesis and the Fathers’ commentaries. This vision, actually original, can be found in the writings of the hagiographers which present the saints in the wild nature. In their quest to spirituality, away from the civilized world, hermits and monks choose to confront themselves directly to these "wastes". The "desert" is not necessarily seen as the land of "savageness", and is not so far from civilization. Lastly, spaces of incultum are combined with domestic lands in an overall perception of the territory. They prove to be economically essential to the Weak as to the Mighty. The latter express there, especially through hunting, some values on which they base their domination on other men.