It is clear that thought is not free if the profession of certain opinions makes it impossible to earn a living.

As I grew up I became increasingly interested in philosophy, or which [his family] profoundly disapproved. Everytime the subject came up they repeated with unfailing regularity, "What is mind? No matter. What is matter? Never mind." After some fifty or sixty repititions, this remark ceased to amuse me.

It is possible that mankind is on the threshold of a golden age; but, if so, it will be necessary first to slay the dragon that guards the door, and this dragon is religion.

There can't be a practical reason for believing something that is not true.

In mass cruelty, the expulsions of Germans ordered by the Russians fall not very far short of the atrocities perpetrated by the Nazis.

It is not my prayer and humility that you cause things to go as you wish, but by acquiring a knowledge of natural laws.

The first dogma which I came to disbelieve was that of free will. It seemed to me that all notions of matter were determined by the laws of dynamics and could not therefore be influenced by human wills.