“We perceive clearly that theories and hypotheses are not accepted or rejected outright; they have their periods of activity, and then lie dormant for a time, only to be revived in a new form later on.”

“The origin of most neurotic fears can be traced to childhood. The seeds of fear may lie dormant in childhood in the subconscious mind. They sprout forth after some time during some period of crisis or stress.”

“As in Mathematics in general, the really great advances, embodying new ideas of far-reaching fruitfullness, have been due to an exceedingly small number of great men… there are periods when for a long series of centuries no advance was made; when the results obtained in a more enlightened age have been forgotten. We observe the times of revival, when the older learning has been rediscovered, and when the results of the progress made in distinct countries have been made available as the starting points of new efforts and a fresh period of activity.”

“I think we may well have some kind of presence there over a period of time… The level of activity that we see today from a military standpoint, I think, will clearly decline. I think they're in the last throes, if you will, of the insurgency.”

“Science, especially evolutionary sciences, can only proceed from learning about theories of hypotheses that do not stand the test of time.”

“Without these experimental tests, very few physicists would have accepted general relativity. There are many hypotheses in physics of almost comparable brilliance and elegance that have been rejected because they did not survive such a confrontation with experiment. In my view, the human condition would be greatly improved if such confrontations and willingness to reject hypotheses were a regular part of our social, political, economic, religious and cultural lives.”

“To be sure, we have to face at this point an important question; but it is a practical, not a theoretical question; it is the question of whether or not to accept the new linguistic forms. The acceptance cannot be judged as being either true or false because it is not an assertion. It can only be judged as being more or less expedient, fruitful, conducive to the aim for which the language is intended. Judgments of this kind supply the motivation for the decision of accepting or rejecting the kind of entities.”

“I have reexamined the contemporary reports and new evidence which has come to light since Maunder's time and conclude that this 70-year period was indeed a time when solar activity all but stopped. This behavior is wholly unlike the modern behavior of the sun which we have come to accept as normal, and the consequences for solar and terrestrial physics seem to me profound.”

“From the time of Zeno to Simplicius, a period of about nine hundred years, the Stoic philosophy formed the characters of some of the best and greatest men. Finally it became extinct, and we hear no more of it til the revival of letters in Italy.”

“When air is charged with emotions, an attempt to teach is often perceived as a form of judgment and rejection.”