A physicist visits a colleague and notices a horseshoe hanging on the wall above the entrance. 'Do you really believe that a horseshoe brings luck?' he asks. 'No,' replies the colleague, 'but I've been told that it works even if you don't believe in it.'

Truth and clarity are complementary.

Those who are not shocked when they first come across quantum theory cannot possibly have understood it.

It is, indeed, perhaps the greatest prospect of humanistic studies to contribute through an increasing knowledge of the history of cultural development to that gradual removal of prejudices which is the common aim of all science.

Anyone not shocked by quantum mechanics has not yet understood it.

All rising curves that show unwelcome trends in human affairs will approach infinity if extended far enough, but it is we who dictate the curve and not vice versa.

There is no hope for any speculation that does not look absurd at first glance.