Georg Simmel’s legacy is traditionally distinguished between sociological and philosophical works so that researchers have little overlap in his areas of interest with their colleagues.Simmel, however, was different in each of these disciplines. It is particularly evident in the context of his relationship with Kant. His sociology, more relevant before 1908, leads to Kant, while his philosophy (the so-called Lebensphilosophie or ‘philosophy of life’) developed after 1908, is opposed to Kant. This research aims to explain this dichotomy.Many thinkers transitioned from Kant to Simmel’s Lebensphilosophie, including Simmel’s student, Semyon Frank, whose fate resembles that of his teacher in many ways. Frank attended his lectures in 1898, translated and reviewed his works, and wrote about Simmel in his own essays. In general, it is difficult to find a figure among the foreign contemporaries of Frank who had a more significant influence on him than Simmel.In many ways, Frank was Simmel’s Russian counterpart: both were baptized Jews in Christian countries; both passed through a school of controversial opinions in many ways fatal to their destiny; both were exiles, despite their prolificacy and significance, and both were unsteady in their academic statuses, but highly appreciated by their colleagues.Frank is a well-known figure in the history of Russian religious philosophу, but his philosophy in the context of his path from Kantianism to his philosophy of life has not been sufficiently studied. This research also aims to fill this gap and to present Frank to Simmel’s readers.