The test of science is not whether you are reasonable—there would not be much of physics if that was the case—the test is whether it works. And the great point about Newton’s theory of gravitation was that it worked, that you could actually say something about the motion of the moon without knowing very much about the constitution of the Earth.

The scientist … must always be prepared to deal with the unknown. It is an essential part of science that you should be able to describe matters in a way where you can say something without knowing everything.

Time is that which is manufactured by clocks.

Religion divides us, while it is our human characteristics that bind us to each other.

On the most usual assumption, the universe is homogeneous on the large scale, i.e. down to regions containing each an appreciable number of nebulae. The homogeneity assumption may then be put in the form: An observer situated in a nebula and moving with the nebula will observe the same properties of the universe as any other similarly situated observer at any time.

Our humanist attitude should therefore throughout be to stress what we all have in common with each other and relegate quarrelsome religion to the private domain where it can do [less] harm.

The true contrast between science and religion is that science unites the world and makes it possible for people of widely differing backgrounds to work together and to cooperate. Religion, on the other hand, by its very claim to know “The Truth” through “revelation,” is inherently divisive and a creator of separatism and hostility.