?This knowledge which I am giving to you has not come through my mind. Some of it is through inner vision or revelation, and the rest through the teachings of the great ones with whom I lived and whose love and blessings I enjoyed. Revelation is that knowledge which flows from the infinite library of the eternal. This knowledge does not come through the senses, or through the mind. This knowledge comes through inner vision and these visions are based on knowledge which is self-evident, which does not need support, which does not need any other evidence. The Upanishads are called shruti, revelations. Mandukya Upanishad, though the shortest of all Upanishads, is a most revered, profound Upanishad that teaches us how to know four states of consciousness: the waking, dreaming and sleeping states, and Turiya, the fourth state, beyond the first three. In this Upanishad, there is a unique combination of psychology and profound philosophy; a clear exposition and understanding of the four states of consciousness.??Swami Rama