We can't solve today's problems with the mentality that created them.

Many a young lady does not realize just how strong her love for a young man is until he fails to pass the approval test with her parents. There is no fear in love; but perfect love casteth out fear. Of all forms of caution, caution in love is the most fatal. There are only two truly infinite things, the universe and stupidity. And I am unsure about the universe.

Common to all these types is the anthropomorphic character of their conception of God. In general, only individuals of exceptional endowments, and exceptionally high-minded communities, rise to any considerable extent above this level. But there is a third stage of religious experience which belongs to all of them, even though it is rarely found in a pure form: I shall call it cosmic religious feeling. It is very difficult to elucidate this feeling to anyone who is entirely without it, especially as there is no anthropomorphic conception of God corresponding to it.

It is my conviction that pure mathematical construction enables us to discover the concepts and the laws connecting them, which gives us the key to the understanding of nature ... In a certain sense, therefore, I hold it true that pure thought can grasp reality, as the ancients dreamed.

Understanding physics is child's play when compared to understanding child's play.

I'm no more intelligent than the next guy. I'm just more curious.

Never lose a holy curiosity.