Health depends upon the music of one's life. When the mechanism of the body is regular in its rhythm and true in its tone, that is what is called health; and it is irregularity of rhythm and dissonance of tone which is called illness, and which physicians examine by counting the pulse, the beating of the heart, and by sounding the back and listening to the tone. They do these things in their capacity as physicians, not as musicians whose ears are trained to test the rhythm and tone.