Taking the study of perception as his point of departure, Merleau-Ponty was led to recognize that one's own body (le corps propre) is not only a thing, a potential object of study for science, but is also a permanent condition of experience, a constituent of the perceptual openness to the world. He therefore underlines the fact that there is an inherence of consciousness and of the body of which the analysis of perception should take account. The primacy of perception signifies a primacy of experience, so to speak, insofar as perception becomes an active and constitutive dimension.
Merleau-Ponty demonstrates a corporeity of consciousness as much as an intentionality of the body, and so stands in contrast with the dualist ontology of mind and body in René Descartes, a philosopher to whom Merleau-Ponty continually returned, despite the important differences that separate them. In the Phenomenology of Perception Merleau-Ponty wrote: “Insofar as I have hands, feet; a body, I sustain around me intentions which are not dependent on my decisions and which affect my surroundings in a way that I do not choose” (1962, p. 440).
The question concerning corporeity connects also with Merleau-Ponty's reflections on space (l'espace) and the primacy of the dimension of depth (la profondeur) as implied in the notion of being in the world (être au monde; to echo Heidegger's In-der-Welt-sein) and of one's own body (le corps propre).