There is no space without aether, and no aether which does not occupy space.

Proof is an idol before which the mathematician tortures himself.

In any attempt to bridge the domains of experience belonging to the spiritual and physical sides of nature, time occupies the key position.

The pursuit of truth in science transcends national boundaries. It takes us beyond hatred and anger and fear. It is the best of us.

We have found that where science has progressed the farthest, the mind has but regained from nature that which the mind put into nature.

Whatever else there may be in our nature, responsibility toward truth is one of its attributes.

It is a primitive form of thought that things exist or do not exist.