Every solution of a problem raises new unsolved problems.
Every discovery contains an irrational element or a creative intuition.
No book can ever be finished. While working on it we learn just enough to find it immature the moment we turn away from it
It is impossible to speak in such a way that you cannot be misunderstood.
Contrary to the outstanding work of art, outstanding theory is susceptible to improvements.
Our aim as scientists is objective truth; more truth, more interesting truth, more intelligible truth. We cannot reasonably aim at certainty. Once we realize that human knowledge is fallible, we realize also that we can never be completely certain that we have not made a mistake.