The sages would say similarly, "Just for the heaven of it." Just to reach for the highest. Human beings cannot live without challenge. We cannot live without meaning. Everything ever achieved we owe to this inexplicable urge to reach beyond our grasp, do the impossible, know the unknown. The Upanishads would say this urge is part of our evolutionary heritage, given to us for the ultimate adventure: to discover for certain who we are, what the universe is, and what is the significance of the brief drama of life and death we play out against the backdrop of eternity. In haunting words, the Brihadaranyaka declares: You are what your deep, driving desire is. As your desire is, so is your will. As your will is, so is your deed. As your deed is, so is your destiny.