A belief in the existence of the material world is impossible to justify using reason. When I get lost in thoughts on that subject, what happens to me always when I wonder about it, I come to a conclusion that everything we see is a mere phenomenon, that there is nothing outside of us that relates to our fantasies, and I always go back to this question of the Indian king: “Why is there something rather than nothing?”
Jean d’Alembert – Letters to Voltaire