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

We often think that when we have completed our study of one we know all about two, because 'two' is 'one and one.' We forget that we still have to make a study of 'and.'

We have found that where science has progressed the farthest, the mind has but regained from nature that which the mind has put into nature. We have found a strange foot-print on the shores of the unknown. We have devised profound theories, one after another, to account for its origin. At last, we have succeeded in reconstructing the creature that made the foot-print. And Lo! it is our own.

Something unknown is doing we don't know what-that is what our theory amounts to.

Unless the structure of the nucleus has a surprise in store for us, the conclusion seems plain — there is nothing in the whole system of laws of physics that cannot be deduced unambiguously from epistemological considerations.

Schrödinger's wave-mechanics is not a physical theory, but a dodge - and a very good dodge too.

It is one thing for the human mind to extract from the phenomena of nature the laws which it has itself put into them; it may be a far harder thing to extract laws over which it has no control. It is even possible that laws which have not their origin in the mind may be irrational, and we can never succeed in formulating them.