Throughout the 1920s, Walter Benjamin took a great interest in the work of the Jewish religious philosopher Erich Unger, which he considered close to his own thought in some respects. Benjamin cites Unger's understanding of the "psychophysical problem" as an example of their common concerns, that is, Unger's understanding of the problematic relationship between mind and body.¹ In Unger and Benjamin, as in much of early twentieth-century German thought, the traditional problem of commercium mentis et corporis assumes a cultural and existential significance that transcends the intellectual interests of an exclusively scientific investigation into mental processes. First, the psychophysical problem figures in Unger's and Benjamin's attempts at developing a new concept of experience that would allow them to repudiate Kant's relegation of religion to the realm of faith. Second, the psychophysical problem informs Unger's and Benjamin's understanding of "politics' for they maintain that particular psychophysical conditions, or altered states of consciousness, are essential constituents of any "true" form of politics. On the basis of the psychophysiological problem, Unger outlined a political realisation of religious experience in his book Politik und Metaphysik (1921). Having attended Unger's lectures on the topic, Benjamin assumed that this book would be "the most significant piece of writing on politics in our time".²