Sound gives to the consciousness an evidence of its existence, although it is in fact the active part of consciousness itself which turns into sound. The knower, so to speak, becomes known to himself; in other words the consciousness bears witness to its own voice. It is therefore that sound appeals to man. All things being derived from and formed of vibrations have sound hidden within them, as fire is hidden in flint. And each atom of the universe confesses by its tone: "My sole origin is sound." If any solid or sonorous body is struck it will answer back: "I am sound."