It ought not to be unpleasant to say that which one honestly believes or disbelieves. That it so constantly is painful to do so, is quite enough obstacle to the progress of mankind in that most valuable of all qualities, honesty of word or of deed.

No man is any the worse off because another acquires wealth by trade, or by the exercise of a profession; on the contrary, he cannot have acquired his wealth except by benefiting others to the extent of what they considered to be its value.

No slavery can be abolished without a double emancipation, and the master will benefit by freedom more than the freed-man.

A well-worn adage advises those who set out upon a great enterprise to count the cost, yet some of the greatest enterprises have succeeded because the people who undertook them did not count the cost.

In truth, the laboratory is the forecourt of the temple of philosophy, and whoso has not offered sacrifices and undergone purification there has little chance of admission into the sanctuary.

It is better to read a little and thoroughly than cram a crude undigested mass into my head, though it be great in quantity.

The method of scientific investigation is nothing but the expression of the necessary mode of working of the human mind.