Merleau-Ponty opposed the abstract natures of both empiricism, which generalized, and idealism, which denied the direct experience and existence of physical reality. He proclaimed that “the perceiving mind is an incarnate mind,” meaning that it was “in” the body in the sense of being co-incident with the body. Perception is a physical process involving eyes, ears, the nose, the hands, rather than only the mind. His focus was thus on the human body as a perceiving, living part of world, a position theretofore much neglected in philosophical inquiry.

According to Merleau-Ponty, perception is neither abstract nor scientific. Rather, all perception is lived; it is the experience of human beings in the world. Consciousness is, to use a later term, “embodied” and always engaged in perceiving the world. What is “phenomenological” about human experience is that what is perceived cannot be separated from how it is perceived or from how it is described. In conversation with Ferdinand de Saussure (1857–1913), Merleau-Ponty composed The Prose of the World (1969), claiming that meaning is not determined by history but by the subject’s actual experience in the world. Language is itself continually changing as a result of this experience. In The Visible and the Invisible Merleau-Ponty had intended to show how communication and thought can go beyond perception, but he died before completing that project.