In his Letters and Papers from Prison, Bonhoeffer outlined a book he wanted to write. Of course, that book never materialized, but there are tantalizing clues about what he was thinking. In his notes for what would have been Chapter Two, Bonhoeffer sketched out some thoughts about the nature of "authentic transcendence":
Authentic transcendence is the neighbor who is within reach in any given situation.
Our relation to God is not a "religious" relationship to the highest, most powerful, and best Being imaginable -- that is not authentic transcendence -- but our relation to God is a new life in "existence for others," through participation in the being of Jesus. The transcendental is not infinite and unattainable tasks, but the neighbor who is within reach in any given situation ...Authentic transcendence is existence for others.
Authentic transcendence is the neighbor who is within reach in any given situation.
That's a radical redefinition of transcendence, but I think he's absolutely correct.