Prince Evgenii Trubetskoi (1863-1920), one of Russia's great philosophers, exemplified what was best in the Russian religious-philosophical tradition. His lifelong pursuit was ''integral knowledge.'' This ideal affirmed that faith was integral to reason and that inner experience (moral, religious, aesthetic), and not just external sensory experience, offered truthful testimony to the nature of reality--precisely contrary to the reductive positivism and scientism of Trubetskoi's day and ours. Following Vladimir Soloviev he developed the concept of Bogochelovechestvo (divine humanity)--the free human realization of the divine principle in ourselves and in the world (deification)--and found in it the very meaning of life. Trubetskoi strikingly combined religious philosophy with an unwavering commitment to the main principles of liberalism: human dignity, freedom of conscience, the rule of law (based ultimately on natural law), and human perfectibility (progress). He worked tirelessly for a liberal, constitutional Russia. This is the first book in English devoted to Evgenii Trubetskoi's life and thought. It includes a comprehensive introduction, six chapters on his religious-philosophical worldview, and six chapters on an area of religious studies that he inspired--the philosophy of the icon.