It is, in fact, nothing short of a miracle that the modern methods of instruction have not yet entirely strangled the holy curiosity of inquiry.

To punish me for my contempt for authority, fate made me an authority myself.

The most incomprehensible thing about the world is that it is at all comprehensible.

It is the theory that decides what we can observe.

The hardest thing in the world to understand is the income tax.

We should take care not to make the intellect our god; it has, of course, powerful muscles, but no personality.

The important thing is not to stop questioning.

In the middle of difficulty lies opportunity.