If the professors of English will complain to me that the students who come to the universities, after all those years of study, still cannot spell 'friend,' I say to them that something's the matter with the way you spell friend.

One cannot understand... the universality of laws of nature, the relationship of things, without an understanding of mathematics. There is no other way to do it.

The test of all knowledge is experiment.

I believe that a scientist looking at nonscientific problems is just as dumb as the next guy.

Only realistic flight schedules should be proposed, schedules that have a reasonable chance of being met. If in this way the government would not support them, then so be it. NASA owes it to the citizens from whom it asks support to be frank, honest, and informative.

Tell your son to stop trying to fill your head with science - for to fill your heart with love is enough!

If you know that you are not sure, you have a chance to improve the situation. I want to demand this freedom for future generations.