It is surmounting difficulties that makes heroes.

The greatest malfunction of spirit is to believe things.

Time is the best appraiser of scientific work, and I am aware that an industrial discovery rarely produces all its fruit in the hands of its first inventor.

In the realm of scientific observation, luck is granted only to those who are prepared.

You have not succeeded in your experiments, that is all there is to it.

Worship the spirit of criticism. If reduced to itself it is not an awakener of ideas or a stimulant to great things, but, without it, everything is fallible; it always has the last word.

Did you ever observe to whom the accidents happen? Chance favors only the prepared mind.