BORN into a pious Lutheran family, Rudolf Otto (1869-1937) was a profound German thinker notable for his radical ideas on philosophy and theology. His remarkable 1917 work, The Idea of the Holy (Das Heilige), set out to examine the “non-rational” or “super-rational” that lies at the heart of our divine nature. His unique thought deeply appealed to those Europeans experiencing a growing sense of alienation caused by the rise of scientism, atheism and the advance of a dangerous technocracy before which authentic religious values had effectively been sidelined. As Troy Southgate's new book demonstrates, Otto's work explores the more emotional aspects of spirituality and yet when the German used terms such as “the numinous” he was adamant that the mystical experience must not be relegated to the realms of subjective feeling. On the contrary, for whilst this religious phenomenon defies rational explanation it is also an objective reality that merely relies on the senses as a means of distinguishing a better awareness of what can only be described as a transcendent encounter with the divine. The subjectively human, therefore, acts as a signpost to the objectively celestial. It was this unique interpretation which appealed to various other philosophers and theologians such as Nikolai Berdyaev, Martin Heidegger, Carl Jung, Jacques Maritain, Joseph Campbell, Mircea Eliade and Julius Evola.