The whole of nature, in the change of seasons and of night and day, expresses rhythm; and the entire cosmic system shows in its working the law of rhythm. The ever-moving sea and the tides are examples of nature's rhythm. The entire universe being created on these two principles, the greatest appeal that can be made to a living creature is by means of tone and rhythm. The whole mechanism of man's body and the pulsation of his heart, all follow rhythm; this proves that every activity of life is an expression of tone and rhythm. Tone and rhythm constitute music; therefore music should be the principal means of perfecting the education of a child.