In proportion to the development of his individuality, each person becomes more valuable to himself, and is therefore capable of being more valuable to others. . . .

So much barbarism, however, still remains in the transactions of most civilized nations, that almost all independent countries choose to assert their nationality by having, to their inconvenience and that of their neighbors, a peculiar currency of their own.

If it were only that people have diversities of taste, that is reason enough for not attempting to shape them all after one model. But different persons also require different conditions for their spiritual development, and can no more exist healthily in the same moral, than all the varieties of plants can in the same physical, atmosphere and climate.

The peculiarity of the evidence of mathematical truths is that all the argument is on one side.

Education makes a man a more intelligent shoemaker, if that be his occupation, but not by teaching him how to make shoes; it does so by the mental exercise it gives, and the habits it impresses.

The test of real and vigorous thinking, the thinking which ascertains truths instead of dreaming dreams, is successful application to practice.

He must be able to hear them [the counter arguments] from persons who actually believe them; who defend them in earnest, and do their very utmost for them. He must know them in their most plausible and persuasive form; he must feel the whole force of the difficulty which the true view of the subject has to encounter and dispose of; else he will never really possess himself of the portion of truth which meets and removes that difficulty.