 Merleau-Ponty’s first book, The Structure of Behavior (SC), resumes the project of synthesizing and reworking the insights of Gestalt theory and phenomenology to propose an original understanding of the relationship between “consciousness” and “nature”. Whereas the neo-Kantian idealism then dominant in France (e.g., Léon Brunschvicg, Jules Lachelier) treated nature as an objective unity dependent on the synthetic activity of consciousness, the realism of the natural sciences and empirical psychology assumed nature to be composed of external things and events interacting causally. Merleau-Ponty argues that neither approach is tenable: organic life and human consciousness are emergent from a natural world that is not reducible to its meaning for a mind; yet this natural world is not the causal nexus of pre-existing objective realities, since it is fundamentally composed of nested Gestalts, spontaneously emerging structures of organization at multiple levels and degrees of integration. On the one hand, the idealist critique of naturalism should be extended to the naturalistic assumptions framing Gestalt theory. On the other hand, there is a justified truth in naturalism that limits the idealist universalization of consciousness, and this is discovered when Gestalt structures are recognized to be ontologically basic and the limitations of consciousness are thereby exposed. The notion of “behavior”, taken by Merleau-Ponty as parallel to the phenomenological concept of “experience” (in explicit contrast with the American school of behaviorism), is a privileged starting point for the analysis thanks to its neutrality with respect to classical distinctions between the “mental” and the “physiological” (SC: 2/4).