For ten points, name this magnum opus of Martin Buber.
This philosophical work differs from its author's earlier work Daniel in that it focuses much less on the mystical union between man and God and instead embraces the notion of their separate existences. While they are impossible and rare on the inorganic or animal levels, respectively, the title relationships exist between man and other beings and more importantly man and God, but they are sometimes transformed into the less fulfilling "I/It" relationships, which include only a fraction of ourselves. For ten points, name this magnum opus of Martin Buber.
This philosophical work differs from its author's earlier work Daniel in that it focuses much less on the mystical union between man and God and instead embraces the notion of their separate existences.
I and Thou (Ich und Du)