It is my deliberate opinion that the one essential requisite of human welfare in all ways is scientific knowledge of human nature.

As new discoveries are causing all-penetrating physical lights so to abound as that, as has been said, we shall soon not know where in the world to get any darkness, so our new facilities for every sort of communication work to reduce privacy much within its former limits.

I want to be a free rover on the breezy common of the universe.

Authorship has never been with me a matter of choice. I have not done it for amusement, or for money, or for fame, or for any reason but because I could not help it.

If a test of civilization be sought, none can be so sure as the condition of that half of society over which the other half has power.

Wherever the appearance of a conventional aristocracy exists in America, it must arise from wealth, as it cannot from birth. An aristocracy of mere wealth is vulgar everywhere. In a republic, it is vulgar in the extreme.

it matters infinitely less what we do than what we are.