The Kena Upanishad is concerned ''wth the relation of mind-consciousness to Brahman-consciousness,'' writes Sri Aurobindo in his commentary on this work. ''The material world and the physical life exist for us only by virtue of our internal self and our intenal life According as our mental instruments represent to us the external world, according as our vital force in obedience to the mind deals with its impacts and objects, so willbe our outward life and exisence''.