The mystery of the atom has resolved itself into the mystery of light, which is now the greatest mystery of physics. Einstein demonstrated the dependence of time upon the position and speed of motion of an observer. He showed, too, the amazing consequence of placing the latter in a stream of light wherein if he moved with the same velocity as light, the observer would then possess no sense of the passage of time. If this happened, what sort of a sense would he possess? Einstein could not tell us, but the mystic who has conquered mind can. He will possess the sense of eternity. He will live in the eternal, in the Kingdom of Heaven.
-- Notebooks Category 19: The Reign of Relativity > Chapter 4: Time, Space, Causality > # 102
-- Perspectives > Chapter 19: The Reign of Relativity > # 35