Abstract: The author examines the contribution of E. K. Medtner to the development of analytical psychology. The focus is made on what role his ideas and the struggle against anthroposophy of R. Steiner played in establishment of the concept of C. G. Jung on sure ground of the transcendentalism of I. Kant. Special attention is also given to the fact how in the process of interaction with Jung, in the activity and ideology of Medtner have appeared the attributes of synthesizing rationality that characterizes the peculiarities of thought pattern of the prominent Russian philosophers of the late XIX – early XX centuries. The article is structure on the basis of comparative analysis of the sources on the topic, including correspondence between Medtner and Jung. Moreover, the author applies the introduced in the previous works concept of synthesizing rationality for assessing Medtner’s worldview.  The study demonstrates that Medtner’s contribution to the development of analytical psychology is not limited by the moral and financial support of Jung, but also the translation of his works into the Russian language and popularization of his doctrine outside of Switzerland. Most valuable has become the ideological influence. Particularly, Medtner was able to explain to Jung the advantages of transcendental idealism as one of the key components of theoretical foundation for analytical psychology. The article also describes how in the context of interaction with Jung, Medtner was able to realize his pursuance of the synthesis of heterogeneous contents of his own mentality, values of the Russian and German cultures, as well as various ways of philosophical world perception.

Keywords: transcendental idealism, Immanuel Kant, symbolism, synthesizing rationality, analytical psychology, Carl Gustav Jung, Emilii Medtner, Zürich School, Russian philosophy, Musaget