The Master Key System

by Charles F. Haanel

We speak of a bell as a "sounding body," yet we know that all that the bell can do is to produce vibrations in the air. When these vibrations come at the rate of sixteen a second they cause a sound to be heard in the mind. It is possible for the mind to hear vibrations up to the rate of 38,000 a second. When the number increases beyond this all is silence again; so that we know that the sound is not in the bell; it is in our own mind. We speak and even think of the sun as "giving light," yet we know it is simply giving forth energy which produces vibrations in the ether at the rate of four hundred trillion a second, causing what are termed light waves, so that we know that what we call light is simply a mode of motion, and the only light that there is, is the sensation caused in the mind by the motion of these waves. When the number of vibrations increases, the light changes in colour, each change in colour being caused by shorter and more rapid vibrations; so that although we speak of the rose as being red, the grass as being green, or the sky as being blue, we know that these colours exist only in our minds, and are the sensation experienced by us as the result of the vibrations of light. When the vibrations are reduced below four hundred trillion a second, they no longer affect us as light but we experience the sensation of heat.