In this paper, I examine some important features of Brentano’s and Rosenthal’s theories of consciousness and self-consciousness. In particular, I discuss the distinction between mental states and conscious states, and the related question of determining whether all mental states can become conscious states. I interpret Brentano’s theory as a one-level theory of mind which is in keeping with the Cartesian conflation between mental states and consciousness. I argue that the problems arising from Brentano’s position are to a certain extent surpassed by a higher-order theory, so that Rosenthal’s position is more accurate. Nevertheless, I disagree with both in the construal of the consciousness of a mental state as self-consciousness. I develop then the fundamentals for a theory based on the primacy of the organism and its vital world, and of conscious experience as the higher form of mental life, which has, however, its roots in the complex net of mental states which are not conscious states.