Merleau-Ponty's move from phenomenology to ontology, which can also be interpreted as the fulfilment of phenomenology, happens when Merleau-Ponty seeks to understand neither the subject nor the world, nor their relation as a third term, but the primordial in-between, that is, how the subject's being in the world and the world's existence for the subject are upheld by something that encompasses them, which he will call ‘wild being’, or ‘vertical being’. Vertical being is the dimension of encroachment or of the union of incompossibles, the ‘world where everything is simultaneous’ (S, 179), the totum simul of every thing, of every profile (VI, 219). From our discussion of the relation of Merleau-Ponty's later thinking to Heidegger’s, we know we should be careful not to turn Being into a Big Object, a positivity, a congealed infinity or a hidden In-itself. Being is not elsewhere; rather, it is an internal possibility of this world. It is the element, the milieu of things that cannot be reduced to any one thing but only transpires in them. In the words of Gary Madison, replying to Theodore Geraets:

If Being is the inexhaustible source of transcendence, then transcendence as the movement of sense is not something that is bestowed upon beings by the human. Transcendence is not a feature of human existence but a movement within Being as such. The question is: what must Being be so that it is the inexhaustible source of transcendence?

It is in order to acquaint us with this new kind of Being that Merleau-Ponty will revisit the phenomenon of self-sensing, focusing on the chiasm at the heart of our carnal being. Our body as a sensible sentient is, as Merleau-Ponty claims, a ‘remarkable variant’ or a ‘prototype’ of Being so that its constitutive doubling, paradox or chiasm is not one of ‘man’ but one of Being itself (VI, 136).