According to the Upanishads, Brahman or Supreme Reality cannot be defined because it is infinite. It is beyond thought and beyond imagination. It is nothing in the mind and nothing outside the mind, nothing past or present or future. These are only conceptions in time and space. But the nearest conception of Brahman we can have is to say that it is a state of consciousness beyond time when SAT, CIT and ANANDA- Being, Consciousness and Bliss are one.
-Paul Deussen (1845-1919) a direct disciple of Arthur Schopenhauer:
"Whatever may be the discoveries of the scientific mind, none can dispute the eternal truths propounded by the Upanishads. Though they may appear as riddles, the key to solving them lies in our heart and if one were to approach them with an open mind one could secure the treasure as did the Rishis of ancient times"
Arthur Schopenhauer: "In the whole world there is no study so beneficial and so elevating as that of the Upanishads.The Upanishads have been the solace of my life, they will be the solace of my death."
असतो मा सद्गमय, तमसो मा ज्योतिर्गमय, मृत्योर् मा अमृतं गमय
"Lead me from the unreal to the real. Lead me from darkness to light. Lead me from death to immortality" (Brihadaranyaka Upanishad I.3.28)