Moderation in temper is always a virtue; but moderation in principle is always a vice.

To kill an error is as good a service as, and sometimes even better than, the establishing of a new truth or fact

A person who spends more than he earns is a fool

An understanding of the natural world is a source of not only great curiosity, but great fulfilment.

The best revenge is to be unlike him who performed the injury.

To avoid criticism say nothing, do nothing, be nothing.

Those who know, do. Those that understand, teach.

So many people have this idea: I want to achieve something great or be somebody great. And they neglect the step that leads to greatness. They don't honor this step at this moment because they have this idea of some future moment where they are going to be great.

What a man does for others, not what they do for him, gives him immortality.

A crust eaten in peace is better than a banquet partaken in anxiety.

The absent are never without fault, nor the present without excuse.

You can best serve civilization by being against what usually passes for it.

What can't be cured must be endured.

There is a wisdom of the head, and... there is a wisdom of the heart.

All our knowledge begins with the senses, proceeds then to the understanding, and ends with reason. There is nothing higher than reason.

If you don't stand for something you will fall for anything.

There's no sense in being precise when you don't even know what you're talking about.

Drop the idea of becoming someone, because you are already a masterpiece. You cannot be improved. You have only to come to it, to know it, to realize it.

Half the world is composed of people who have something to say and can't, and the other half who have nothing to say and keep on saying it.

Mistakes are always forgivable, if one has the courage to admit them.

Challenges are gifts that force us to search for a new center of gravity. Don't fight them. Just find a new way to stand.