If we want to solve a problem that we have never solved before, we must leave the door to the unknown ajar.

When you're thinking about something that you don't understand, you have a terrible, uncomfortable feeling called confusion... Now, is the confusion's because we're all some kind of apes that are kind of stupid working against this, trying to figure out [how] to put the two sticks together to reach the banana and we can't quite make it... So I always feel stupid. Once in a while, though, the sticks go together on me and I reach the banana.

Words can be meaningless. If they are used in such a way that no sharp conclusions can be drawn.

I'm trying to find out NOT how Nature could be, but how Nature IS.

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.

Of course, you only live one life, and you make all your mistakes, and learn what not to do, and that's the end of you.

Some things that satisfy the rules of algebra can be interesting to mathematicians even though they don't always represent a real situation.