“If we all worked on the assumption that what is accepted as true is really true, there would be little hope of advance.”

“Physics advances by accepting absurdities. Its history is one of unbelievable ideas proving to be true.”

“True love would look a second time. True love would not be thwarted. True love would not accept no for an answer.”

“If we can't accept what we don't know, there really is no hope.”

“Pure mathematics consists entirely of assertions to the effect that, if such and such a proposition is true of anything, then such and such another proposition is true of that thing. It is essential not to discuss whether the first proposition is really true, and not to mention what the anything is, of which it is supposed to be true. [...] Thus mathematics may be defined as the subject in which we never know what we are talking about, nor whether what we are saying is true. People who have been puzzled by the beginnings of mathematics will, I hope, find comfort in this definition, and will probably agree that it is accurate.”

“If that (to travel hopefully is better to arrive) were true, and known to be true, how could anyone travel hopefully? There would be nothing to hope for.”