A half-truth is the most cowardly of lies.

A railroad is like a lie you have to keep building it to make it stand.

By law of periodical repetition, everything which has happened once must happen again and again -- and not capriciously, but at regular periods, and each thing in its own period, not another's and each obeying its own law.

I am the entire human race compacted together. I have found that there is no ingredient of the race which I do not possess in either a small way or a large way.

It is impossible that a genius - at least a literary genius - can ever be discovered by his intimates; they are so close to him that he is out of focus to them and they can't get at his proportions; they can't perceive that there is any considerable difference between his bulk and their own.

Part of the secret of a success in life is to eat what you like and let the food fight it out inside.

Evolution is the law of policies: Darwin said it, Socrates endorsed it, Cuvier proved it and established it for all time in his paper on The Survival of the Fittest. These are illustrious names, this is a mighty doctrine: nothing can ever remove it from its firm base, nothing dissolve it, but evolution.