Perhaps no concept is more central to maurice merleau-ponty's philosophy than his concept of depth. not only did merleau-ponty recognize the philosophical significance of depth for articulating a phenomenology of perception, but he saw it as essential for pursuing and expressing a novel, radical ontology. depth, merleau-ponty writes, is ``the most existential dimension,'' ``the dimension of dimensions''; it is the ``sine qua non'' of the world and being. let me elucidate merleau-ponty's radical concept of depth by ``addressing'' the salient contexts in which he approached this notion. in the first part of this paper, i shall examine depth in the experience of perception and schizophrenia. in the second, i shall discuss depth as descriptive of an ontology of ``flesh'' and as the guiding theme for the philosophical enterprise.