Purpose. The main purpose of the study is to examine Kant’s first experience in creating a methodology for determining the holistic, spiritual nature of man, firstly, in terms of identifying the range of phenomena that should be included in the analysis of the spiritual essence of man, and secondly, this experience may be indicative for identifying dead ends in the research of spirituality of modern philosophers. Theoretical basis. The study is based on the methodology of philosophical anthropology formulated by M. Scheler, which, on the one hand, integrates the achievements of philosophy of life, phenomenology, existentialism and philosophical hermeneutics, and on the other hand, is based on the premise of the initial direct unity of the opposition of mental and physiological processes of human life. The basis for further expansion of the theoretical framework is the experience of spiritual practices of the Ancient East and religious practices of the Christian Middle Ages. Particularly noteworthy is the experience of modern psychotherapeutic practices, which, for all their diversity, have their roots in the depths of primitive beliefs and mysteries of ancient civilisations, and the tips of their branches reaching to the ideas of modern transpersonal psychology. Originality. Firstly, the author uses M. Scheler’s ideas about the spiritual nature of man and the unity of his essential forces: corporeality, senses, feelings, thinking, values of worldview principles and the Absolute to analyse Kant’s anthropological concept. Secondly, Kant’s position on the way of describing human nature reveals contradictions. These contradictions are caused, on the one hand, by the prevailing mechanistic picture of the world, and, on the other hand, by the philosopher’s intuitive assumptions that did not follow from the provisions of his dualistic position (the concepts of mind and soul as used in Kant’s work "Anthropology from a Pragmatic Point of View"). Thirdly, the author identifies those fragments of the said work where Kant assumes the presence of corporeality, but does not clearly formulate its role in building the integral nature of the spiritual man. Conclusions. Immanuel Kant was one of the first to raise the issue of the primary study of human nature in comparison with issues of ontology, epistemology, morality, etc. However, the philosopher failed to create a concept of holistic human nature, the essence of which would be its spiritual core. Kant based his methodology of studying human nature on the dualistic opposition of the essential forces of man. This methodology was conditioned by the dominant mechanistic picture of the world. Kant’s researches in the field of morality, aesthetics, and science were carried out in the cognitive-theoretical plane, so they were unable to reach a true synthesis of the essential forces of man by their methodology. Such a synthesis is possible on the basis of spiritual practice. The results of the study of the experience of the achievements and mistakes of the outstanding philosopher in the study of human nature open up the possibility of further refinement and development of philosophical and anthropological methodology in understanding the spiritual nature of man as a whole through comprehension of the mechanism of spiritual practice and, on this basis, understanding of the phenomenon of spirituality in all historical forms of its manifestation.