Medieval philosophers spoke metaphorically of the "music of the spheres." Johannes Kepler discovered physical harmonies in planetary motion when he calculated that the difference between the maximum and minimum angular speeds of a planet in its orbit approximated a harmonic proportion. Kepler explained the Earth's small harmonic range as:
"The Earth sings Mi, Fa, Mi: you may infer even from the syllables that in this our home misery and famine hold sway."
At very rare intervals all of the planets can produce sound in "perfect concord" and Kepler proposed that this may have happened perhaps only once, at the time of creation. This sound may not be audible but has harmonic, mathematical and religious significance.
In Hindu religious texts, particularly the Upanishads, Om is designated as the Ultimate Reality in aspects of sound and word. The Hindus believe that before Brahman created the Universe, the entire Cosmos was pervaded by an emptiness or void, also known as "Shunyākāsha" (literally, “no sky). In this state of nothingness, the seed of life existed in latent potency. At the time of creation, this seed of Universal Consciousness was first manifested as the cosmic vibration, Om.