This is the secret of all secrets. UPANISHADS... The word UPANISHAD itself means 'secret doctrine'. Why call it secret if you are going to call it doctrine? If it is a doctrine, it cannot be secret; if it is secret, it cannot be a doctrine. So why call it a secret doctrine? Why use two contradictory words? Mystics have always thought that the moment you use a word without also using its opposite, you divide life. And life exists in contradictions. The negative and positive of electricity exist in deep communion; the male psyche and the female psyche exist in deep communion. Darkness and light - we may think they are contradictions, opposites, polar opposites, but they exist in deep communion.