To gain knowledge of concentration requires not only study, but balance also. Before touching this subject I would first like to explain what motive we have behind concentration. There are two aspects of life: the audible life and the silent life. By audible life I mean all experiences, all sensations that we experience through our five senses. This is distinct from the life which I would call the silent life. And when one asks what benefit one derives from getting in touch with the silent life, the answer is that the benefit is as abstract as the silent life itself. The life of sensation is clear; its benefit is clear; and yet as limited as is the life of sensation, so limited is its benefit. That is why in the end we find all our experiences of little value. Their importance lasts as long as we experience them; but after that the importance of the life of sensation is finished.