The theory of the oblique function that Architecture Principe began developing in 1963 established a new relationship with the ground based on instability and unbalance. The oblique gives a new importance to the ground: the sloped plane makes it possible to create a surface with a broader range of uses. Becoming both floor and partition, the livable space provides a support for the free movement of the individual and his personal “potential load,” enabling him to be in a state of receptiveness, participation and adhesion to an architectural dynamic. Several diagrams show the oblique, freed of any obstacle, supporting a body that adheres with all its weight to an “inclined” surface. Les Vagues (The Waves, 1965-1966) were the first series illustrating this principle developed on an urban scale, with huge artificial hills that must be “climbed” or “overcome” positioned along a cantilevered pathway. In the drawings done by Claude Parent these hills resemble tectonic upthrusts, whose irruption seems to break the horizontal monotony. In these irregular landscapes, continuity and rupture are reconciled thanks to the association of the oblique with the “fault,” the void created between the volume masses imbuing them with movement and dynamism: “Thus, from one fault to the next, from void to void, people levitate,” wrote Parent.