The problem of creating something new, but which is consistent with everything which has been seen before, is one of extreme difficulty.

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.

Observation, reason, and experiment make up what we call the scientific method.

To test whether you have learned an idea or a definition, rephrase what you just learned without using the new word.

When a scientist doesn't know the answer to a problem, he is ignorant. When he has a hunch as to what the result is, he is uncertain. And when he is pretty darn sure of what the result is going to be, he is in some doubt.

If you're doing an experiment, you should report everything that you think might make it invalid - not only what you think is right about it; other causes that could possibly explain your results; and things you thought of that you've eliminated by some other experiment, and how they worked -to make sure the other fellow can tell they have been eliminated.

If an apple was magnified to the size of the Earth, then the atoms in the apple would be approximately the size of the original apple.