The theory of the vibrating universe became popular in occultism in the nineteenth century, following discoveries about the nature of light, electricity and magnetism. In the early years of the century physicists demonstrated that light moves in waves and that electrical and magnetic impulses also travel in waves or undulations. At the same period it was accepted that the molecules of all substances are in a state of constant oscillating movement. Building on these ideas, occultists developed the theory that everything in the universe is undulating or vibrating. Different things vibrate at different rates of speed, and the essential nature or character of each thing is determined by its rate of vibration, in the same way that the different colours which we see are determined by differing wavelengths of light.

–Richard Cavendish, The Black Arts: A Concise History of Witchcraft, Demonology, Astrology, and Other Mystical Practices