"The optimist believes that this is the best of all possible worlds, and the pessimist fears that this might be the case."

“It is a testimony to the power of education that classical mechanics could operate for so long under a mistaken conception. Teaching and research concentrated on integrable systems, each feeding the other, until in the end we had no longer the tools nor the interest for studying nonintegrable systems.”

“Well, it has been a long time since manna last fallen from from heaven. We cannot live alone; we rely on others to produce the stuff of our material and intellectual life, and we have to organize society so that its members will cooperate toward the common good.”

“Nowadays, however, we are much more aware of the fact that the best proof in the world is worth no more than its premises: every scientific theory is transitory and provisional, in wait for a better one, and accepted only as long as the experimental results conform to its predictions.”

“The world is full, at every scale, and every scale ignores the higher and lower ones.”

“So every possible reality, once God gives it existence, will reveal its own identity. Its life will unfold slowly, whereas God encompasses it at a single glance.”

“If there is a God, he has left no tracks in the laws of physics; or if he has, he has covered them up very well.”