Mental health, in one awake, guarantees that person knowledge of the central phenomenon-contents of his own mind, under an adequate classificatory heading. This is the primary thesis of the paper. That knowledge is not itself a phenomenon-content, and usually is achieved in no way. Rather, it stems from the natural accessibility of mental phenomenon-contents to wakeful consciousness. More precisely, when mental normality obtains, such knowledge necessarily obtains in wakeful consciousness. This thesis conjoins a version of Cartesianism with the concepts of (...) mental health and human nature. Demonstration of the thesis requires that we show that a particular human mental potential fails fully to be realized when such self-awareness is impaired. That potential is for consciousness of the world (w-Cs), wakefulness. W-Cs divides into consciousness of the outer world (ow-Cs), and consciousness of the inner world (iw-Cs), and we need to demonstrate an essential dependence of ow-Cs upon iw-Cs. Now w-Cs is the adoption of the correct occurrent epistemological posture to the world, and this involves free rational determination of occurrent cognitive attitudes via the internal systematized knowledge of the world, which requires adequate awareness of mental phenomenon-contents. Therefore ow-Cs needs iw-Cs. This is displayed in mental structural accounts of hypnotic, drunken, and psychotic disturbances of consciousness. (For we endorse a structural account of mental health.) We show how failures of self-consciousness entail disturbed modes of determination of cognitive attitudes by the knowledge-system, which is loss of contact with the personal yet true internal representation of the world, which is loss of contact with reality, which is a disturbance both of w-Cs and of consciousness itself. (shrink)