The belief in an external world independent of the perceiving subject is the basis of all natural science. Since, however, sense perception only gives information of this external world or of "physical reality" indirectly, we can only grasp the latter by speculative means. It follows from this that our notions of physical reality can never be final. We must always be ready to change these notions - that is to say, the axiomatic basis of physics - in order to do justice to perceived facts in the most perfect way.
I believe in intuition and inspiration. Imagination is more important than knowledge. For knowledge is limited, whereas imagination embraces the entire world, stimulating progress, giving birth to evolution. It is, strictly speaking, a real factor in scientific research.
Every kind of peaceful cooperation among men is primarily based on mutual trust and only secondarily on institutions such as courts of justice and police.
I consider it important, indeed urgently necessary, for intellectual workers to get together, both to protect their own economic status and, also, generally speaking, to secure their influence in the political field.
An attempt at visualizing the Fourth Dimension: Take a point, stretch it into a line, curl it into a circle, twist it into a sphere, and punch through the sphere.
I was very pleased with your kind letter. Until now I never dreamed of being something like a hero. But since you've given me the nomination I feel that I am one.
It is not a lack of real affection that scares me away again and again from marriage. Is it a fear of the comfortable life, of nice furniture, of dishonor that I burden myself with, or even the fear of becoming a contented bourgeois.
I want to know how God created this world. I am not interested in this or that phenomenon, in the spectrum of this or that element. I want to know God's thoughts, the rest are details.
Then there are the fanatical atheists whose intolerance is of the same kind as the intolerance of the religious fanatics and comes from the same source.
If you want your children to be smart, tell them stories. If you want them to be really smart, tell them more stories. If you want your children to be brilliant, tell them even more stories.
To one bent on age, death will come as a release. I feel this quite strongly now that I have grown old myself and have come to regard death like an old debt, at long last to be discharged.