“Is there any knowledge in the world that is so certain that no reasonable man could doubt it?”

The hardest thing to learn in life is which bridge to cross and which to burn.

Freedom of opinion can only exist when the government thinks itself secure.

Most people would sooner die than think; in fact, they do so.

If there were in the world today any large number of people who desired their own happiness more than they desired the unhappiness of others, we could have paradise in a few years.

I hate being all tidy like a book in a library where nobody reads – prison is horribly like that.

Philosophy, from the earliest times, has made greater claims, and achieved fewer results, than any other branch of learning.

No nation was ever so virtuous as each believes itself, and none was ever so wicked as each believes the other.

I consider the official Catholic attitude on divorce, birth control, and censorship exceedingly dangerous to mankind.

Even if all the experts agree, they may well be mistaken.

Few people can be happy unless they hate some other person, nation, or creed.

Sometimes the hardest thing in life is to know which bridge to cross and which to burn.

It seems to me fundamental dishonesty, and a fundamental treachery to intellectual integrity to hold a belief because you think it’s useful and not because you think it’s true.

The fundamental concept in social science is power, in the same sense in which energy is the fundamental concept in physics.

To be able to fill leisure intelligently is the last product of civilization, and at present, very few people have reached this level.

Dogmatism is the greatest of mental obstacles to human happiness.

There are two motives for reading a book; one, that you enjoy it; the other, that you can boast about it.

A little doubt is better than total credulity.

My main thing is to prove all the doubters wrong.

There has been a lot of self-doubt and unwelcome events in my life.

The play will invariably be different and stronger, and much more fulfilling and richer on all counts. There’s no doubt in my mind about it.

I hope you never doubt again that even when you are in pain, that you are a miracle, that every part of you is incredible.

I could have been the next Babe Ruth. No doubt about it.

I mean just out and out crooks. And the next generation had a little more finesse. But I mean those first wave of people, you know, definitely would take all your money, no doubt about it.

Sometimes if I tell people, ‘I’m afraid that I’m really a fraud,’ or ‘I have a lot of self-doubt,’ they go.