Is there an explanation of why man rejoices, or why he is impressed by the music played to him? Is it only an amusement, or a pastime? No, there is something else besides it. The principal reason is that in man there is a perpetual rhythm going on, which is the sign of life in him, a rhythm which is expressed in his pulsation and in his heart-beats, even in his heart. Upon this rhythm depends his health - not only his health, but his moods. Therefore, anywhere, a continued rhythm must have an effect upon every person, and upon every person its effect is distinct and different.