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

It is surprising that people do not believe that there is imagination in science. It is a very interesting kind of imagination, unlike that of the artist. The great difficulty is in trying to imagine something that you have never seen, that is consistent in every detail with what has already been seen, and that is different from what has been thought of; furthermore, it must be definite and not a vague proposition. That is indeed difficult.

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

The work I have done has, already, been adequately rewarded and recognized. Imagination reaches out repeatedly trying to achieve some higher level of understanding, until suddenly I find myself momentarily alone before one new corner of nature's pattern of beauty and true majesty revealed. That was my reward.

There in wine is found the great generalization: all life is fermentation.

If all of mathematics disappeared, physics would be set back by exactly one week.

Science is a process for learning about nature in which competing ideas about how the world works are measured against observations.