Do what you can to do what you ought, and leave hoping and fearing alone.

Surely it must be plain that an ingenious man could speculate without end on both sides, and find analogies for all his dreams. Nor does it help me to tell me that the aspirations of mankind

There is assuredly no more effectual method of clearing up one's own mind on any subject than by talking it over, so to speak, with men of real power and grasp, who have considered it from a totally different point of view.

Sit down before fact as a little child, be prepared to give up every conceived notion, follow humbly wherever and whatever abysses nature leads, or you will learn nothing.

The secret of genius is to carry the spirit of childhood into maturity.

What men of science want is only a fair day's wages for more than a fair day's work.

The ultimate court of appeal is observation and experiment... not authority.