'The treatise on the Trinity occupies a rather isolated position in the total dogmatic system. To put it crassly, and not without exaggeration, when the treatise is concluded, its subject is never brought up again. Its function in the whole dogmatic construction is not clearly perceived. It is as though this mystery has been revealed for its own sake, and that even after it has been made known to us, it remains, as a reality, locked up within itself. We make statements about it, but as a reality it has nothing to do with us at all.'