It is weakness, says the Vedanta, which is the cause of all misery in this world. Weakness is the one cause of suffering. We become miserable because we are weak. We lie, steal, kill and commit other crimes, because we are weak. We die because we are weak. Where there is nothing to weaken us, there is no death nor sorrow. We are miserable through delusion. Give up the delusion and the whole thing vanishes.
