There is no history, only histories.

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.

The only way to test a hypothesis is to look for all the information that disagrees with it.

If we wish our civilization to survive we must break with the habit of deference to great men.

It can't happen here is always wrong: a dictatorship can happen anywhere.

It is wrong to think that belief in freedom always leads to victory; we must always be prepared for it to lead to defeat. If we choose freedom, then we must be prepared to perish along with it.

The future is always present, as a promise, a lure and a temptation.