At the core of Merleau-Ponty's later unfinished work, his revisioned ontology The Visible and the Invisible, is the controversial reversibility thesis. To fully grasp what Merleau-Ponty intends by this thesis and what philosophical work he hopes it will achieve, it is necessary to consider what motivated him in this revisioning and also to situate it within his overall project. Why was he not satisfied with his earlier works which sought to undercut the dualist oppositions of mind/body, self/other, interior/exterior, subject/object, immanence/transcendence, and so on? Resolving these oppositions is at the heart of Merleau-Ponty's overall philosophical project—to refute dualism and monism once and for all, so that philosophy is neither menaced by scepticism nor reduced to solipsism. As philosopher Emmanuel de Saint Aubert attests on the basis of an interview with Merleau-Ponty the year before his untimely death, "since the beginning, the choice of perception as the major theme of his work is subordinated to the problem of the relation between the soul and the body: perception is one of the best ways of expressing this "mélange" of the body and mind' (de Saint Aubert 2005). Thus, Merleau-Ponty's efforts towards the resolution of this problem begin with perception and with the lived body, which is not a mere object in the world apart from the knowing subject but which nonetheless represents a point of view. Knowing/perceiving subjects thus are located in place and time and as such consciousness takes on a "certain physical and historical situation' (Pri.P:5, RMM:403). The reversibility thesis must solve a number of inherited and potential issues for Merleau-Ponty, beginning with two arising directly from his thesis of the Primacy of Perception.