Let us begin by describing the spatiality of one's own body. If my arm is resting on the table, I will never think to say that it is next to the ashtray in the same way that the ashtray is next to the telephone. The contour of my body is a border that ordinary spatial relations do not cross. This is because the body's parts relate to each other in a peculiar way: they are not laid out side by side, but rather envelop each other. My hand, for example, is not a collection of points. In cases of allochiria,1 where the subject senses in his right hand the stimulus that is applied to his left hand, it is impossible to suppose that each of the stimulations individually changes its spatial value,2 and the various points on the left hand are transported to the right insofar as they fall within a total organ, within a hand without parts that was displaced all at once. The points, then, form a system, and the space of my hand is not a mosaic of spatial values. Likewise, my entire body is not for me an assemblage of organs juxtaposed in space. I hold my body as an indivisible possession and I know 101the position of each of my limbs through a body schema [un schéma corporel]3 that envelops them all. But the notion of the “body schema” is ambiguous, as are all concepts that appear at turning points in science. They can only be fully developed given a reform of methodology. At first they are employed in a sense that is not yet their full sense, and their immanent development is what breaks up previous methods.