For instance, what is sound? The different notes are the various degrees of breath, human breath or the echo coming from a vessel or instrument or bell, for that also is breath; the breath of human beings as well as the breath of objects; from the one breath many sounds manifest. So that takes one back to the idea of unity again. All this variety of colors and forms and sounds proceeds from one single Source. Associated with this there is the question of the mysticism of number. This is the idea of rhythm. Every movement must have its rhythm. There cannot be movement without rhythm. By rhythm we imagine the intervals of time, such as 'hour' or 'minute,' or in music 'crochet,' 'quaver,' 'semi-breve,' for all these arise from our habit of dividing time into a rhythm. We do this because our life itself depends on rhythm. Our self is full of rhythm. The beating of the pulse, of the heart, in the head, all show life's rhythm.