If a man cannot see a church, it is preposterous to take his opinion about its altar-piece or painted window.

Books are the money of Literature, but only the counters of Science.

The known is finite, the unknown infinite; intellectually we stand on an islet in the midst of an illimitable ocean of inexplicability. Our business in every generation is to reclaim a little more land, to add something to the extent and the solidity of our possessions.

A man's worst difficulties begin when he is able to do as he likes.

In scientific work, those who refuse to go beyond fact rarely get as far as fact.

I can assure you that there is the greatest practical benefit in making a few failures early in life. You learn that which is of inestimable importance that there are a great many people in the world who are just as clever as you are. You learn to put your trust, by and by, in an economy and frugality of the exercise of your powers, both moral and intellectual; and you very soon find out, if you have not found it out before, that patience and tenacity of purpose are worth more than twice their weight of cleverness.

The besetting sin of able men is impatience of contradiction and of criticism. Even those who do their best to resist the temptation, yield to it almost unconsciously and become the tools of toadies and flatterers. "Authorities," "disciples," and "schools" are the curse of science and do more to interfere with the work of the scientific spirit than all its enemies.