Born in Peine (near Hannover) in 1869 you get a stickler religious education and decided very early to be a Protestant pastor. She went to college at the universities of Erlangen and Göttingen, beginning in the historical approach, developed with the guidance of teachers and R. Smend or Th. Haring. It is well entrenched in historical criticism applied to biblical texts, laying the foundations for future study of religions. His first publications are devoted to the intuitive vision of the Holy Spirit in Luther (1898) and The Philosophy of Religion in Kant and Fries and its application to theology (1909). An important role in the formation and development of his ideas took art history and music, as well as to undertake extensive travel throughout his life (Africa, Japan, China, India). The publication in 1917 of his most famous work, The holy coincides with his acceptance of the chair of theology at the University of Marburg. There was a time, theologian, philosopher of religion, a psychologist and historian of religions. Otto was a versatile man. The same edited a collection of liturgical prayers writing about the most exalted theoretical issues. He even had time moved by his ecumenical concern, to found the "League of religious humanity." Always believed possible an understanding between the different religions. The last years of his life were devoted to to present their research on Eastern religious world in books such as Eastern and Western Mysticism and Indian Religion of Grace and Christianity. Also in 1934 he published a critical edition of the Bhagavad-Gita. Notable are his comparative analysis between the mysticism of Meister Eckhart and the mysticism of Eastern religions. He died in 1937.