The article provides a meaningful analysis of one of the last monographic works of Doctor of Psychology, Professor R. M. Nagdyan (Republic of Armenia). The monograph consistently substantiates the possibility of applying a metaphysical approach to the study of minerals from the positions of psychology, philosophy, and additional sciences; propensity for errors of scientists to metaphysics. The study presents productive metaphysical possibilities for solving the problem of the adequacy of mental reflection in studies of various philosophical and psychological ideas about the relationship between the external world and the “image of the world”. From the standpoint of the metaphysical approach, the author shows the general scientific significance of the principle of symmetry as a universal tool for cognition; the applied possibilities of the metaphysically substantiated principle of symmetry in the construction of the author’s concept of education are also given. Analysis of the content of the monograph by R. M. Nagdyan is accompanied by relevant comparisons with modern studies of the problem of consciousness in psychology.