The most important of my discoveries have been suggested to me by failures.

I have learned more from my mistakes than from my successes.

The wealth and prosperity of the country are only the comeliness of the body, the fullness of the flesh and fat; but the spirit is independent of them; it requires only muscle, bone and nerve for the true exercise of its functions. We cannot lose our liberty, because we cannot cease to think.

Language is not only the vehicle of thought, it is a great and efficient instrument in thinking.

Nothing is so dangerous to the progress of the human mind than to assume that our views of science are ultimate, that there are no mysteries in nature, that our triumphs are complete and that there are no new worlds to conquer.

Natural science is founded on minute critical views of the general order of events taking place upon our globe, corrected, enlarged, or exalted by experiments, in which the agents concerned are placed under new circumstances, and their diversified properties separately examined. The body of natural science, then, consists of facts; is analogy,-the relation of resemblance of facts by which its different parts are connected, arranged, and employed, either for popular use, or for new speculative improvements.

We must reason in natural philosophy not from what we hope, or even expect, but from what we perceive.