The successful conduct of an industrial enterprise requires two quite distinct qualifications: fidelity and zeal.

Truth gains more even by the errors of one who, with due study and preparation, thinks for himself, than by the true opinions of those who only hold them because they do not suffer themselves to think.

Unfortunately for the good sense of mankind, the fact of their fallibility is far from carrying the weight in their practical judgement, which is always allowed to it in theory; for while every one well knows himself to be fallible, few think it necessary to take any precautions against their own fallibility.

The study of science teaches young men to think, while study of the classics teaches them to express thought.

A [psychological] difficulty is not an impossibility.

If two or more instances of the phenomenon under investigation have only one circumstance in common, the circumstance in which alone all the instances agree is the cause (or effect) of the given phenomenon.

The idea that truth always triumphs over persecution is one of those pleasant falsehoods, which most experience refutes. History is teeming with instances of truth put down by persecution. If not put down forever, it may be set back for centuries.