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Maurice Merleau-Ponty (French: [moRis meRlo poti]; 14 March 1908 - 3 May 1961) was a French phenomenological philosopher, strongly influenced by Edmund Husserl and Martin Heidegger. The constitution of meaning in human experience was his main interest and he wrote on perception, art, and politics. He was on the editorial board of Les Temps modernes, the leftist magazine established by Jean-Paul Sartre in 1945. At the core of Merleau-Ponty's philosophy is a sustained argument for the foundational role perception plays in understanding the world as well as engaging with the world.

In his Phenomenology of Perception (first published in French in 1945), Merleau-Ponty developed the concept of the body-subject (le corps propre) as an alternative to the Cartesian "ego cogito." This distinction is especially important in that Merleau-Ponty perceives the essences of the world existentially. Consciousness, the world, and the human body as a perceiving thing are intricately intertwined and mutually "engaged." The phenomenal thing is not the unchanging object of the natural sciences, but a correlate of our body and its sensory-motor functions. Taking up and "communing with" (Merleau-Ponty's phrase) the sensible qualities it encounters, the body as incarnated subjectivity intentionally elaborates things within an ever-present world frame, through use of its pre-conscious, pre-predicative understanding of the world's makeup. The elaboration, however, is "inexhaustible" (the hallmark of any perception according to Merleau-Ponty). Things are that upon which our body has a "grip" (prise), while the grip itself is a function of our connaturality with the world's things. The world and the sense of self are emergent phenomena in an ongoing "becoming."  The essential partiality of our view of things, their being given only in a certain perspective and at a certain moment in time does not diminish their reality, but on the contrary establishes it, as there is no other way for things to be copresent with us and with other things than through such "Abschattungen" (sketches, faint outlines, adumbrations). The thing transcends our view, but is manifest precisely by presenting itself to a range of possible views. The object of perception is immanently tied to its background--to the nexus of meaningful relations among objects within the world. Because the object is inextricably within the world of meaningful relations, each object reflects the other (much in the style of Leibniz's monads). Through involvement in the world - being-in-the-world - the perceiver tacitly experiences all the perspectives upon that object coming from all the surrounding things of its environment, as well as the potential perspectives that that object has upon the beings around it.  Each object is a "mirror of all others." Our perception of the object through all perspectives is not that of a propositional, or clearly delineated, perception; rather, it is an ambiguous perception founded upon the body's primordial involvement and understanding of the world and of the meanings that constitute the landscape's perceptual gestalt. Only after we have been integrated within the environment so as to perceive objects as such can we turn our attention toward particular objects within the landscape so as to define them more clearly. This attention, however, does not operate by clarifying what is already seen, but by constructing a new Gestalt oriented toward a particular object. Because our bodily involvement with things is always provisional and indeterminate, we encounter meaningful things in a unified though ever open-ended world.  From the time of writing Structure of Behavior and Phenomenology of Perception, Merleau-Ponty wanted to show, in opposition to the idea that drove the tradition beginning with John Locke, that perception was not the causal product of atomic sensations. This atomist-causal conception was being perpetuated in certain psychological currents of the time, particularly in behaviourism. According to Merleau-Ponty, perception has an active dimension, in that it is a primordial openness to the lifeworld (the "Lebenswelt").  This primordial openness is at the heart of his thesis of the primacy of perception. The slogan of Husserl's phenomenology is "all consciousness is consciousness of something", which implies a distinction between "acts of thought" (the noesis) and "intentional objects of thought" (the noema). Thus, the correlation between noesis and noema becomes the first step in the constitution of analyses of consciousness. However, in studying the posthumous manuscripts of Husserl, who remained one of his major influences, Merleau-Ponty remarked that, in their evolution, Husserl's work brings to light phenomena which are not assimilable to noesis-noema correlation. This is particularly the case when one attends to the phenomena of the body (which is at once body-subject and body-object), subjective time (the consciousness of time is neither an act of consciousness nor an object of thought) and the other (the first considerations of the other in Husserl led to solipsism).  The distinction between "acts of thought" (noesis) and "intentional objects of thought" (noema) does not seem, therefore, to constitute an irreducible ground. It appears rather at a higher level of analysis. Thus, Merleau-Ponty does not postulate that "all consciousness is consciousness of something", which supposes at the outset a noetic-noematic ground. Instead, he develops the thesis according to which "all consciousness is perceptual consciousness". In doing so, he establishes a significant turn in the development of phenomenology, indicating that its conceptualisations should be re-examined in the light of the primacy of perception, in weighing up the philosophical consequences of this thesis.  The highlighting of the fact that corporeity intrinsically has a dimension of expressivity which proves to be fundamental to the constitution of the ego is one of the conclusions of The Structure of Behavior that is constantly reiterated in Merleau-Ponty's later works. Following this theme of expressivity, he goes on to examine how an incarnate subject is in a position to undertake actions that transcend the organic level of the body, such as in intellectual operations and the products of one's cultural life.  He carefully considers language, then, as the core of culture, by examining in particular the connections between the unfolding of thought and sense--enriching his perspective not only by an analysis of the acquisition of language and the expressivity of the body, but also by taking into account pathologies of language, painting, cinema, literature, poetry and song.  This work deals mainly with language, beginning with the reflection on artistic expression in The Structure of Behavior--which contains a passage on El Greco (p. 203ff) that prefigures the remarks that he develops in "Cezanne's Doubt" (1945) and follows the discussion in Phenomenology of Perception. The work, undertaken while serving as the Chair of Child Psychology and Pedagogy at the University of the Sorbonne, is not a departure from his philosophical and phenomenological works, but rather an important continuation in the development of his thought.  As the course outlines of his Sorbonne lectures indicate, during this period he continues a dialogue between phenomenology and the diverse work carried out in psychology, all in order to return to the study of the acquisition of language in children, as well as to broadly take advantage of the contribution of Ferdinand de Saussure to linguistics, and to work on the notion of structure through a discussion of work in psychology, linguistics and social anthropology.

what did he write in what he published?
Consciousness, the world, and the human body as a perceiving thing are intricately intertwined and mutually "engaged."