Science is what we know, and philosophy is what we don't know.

Laughter is the most inexpensive and most effective wonder drug. Laughter is a universal medicine.

Nothing is so exhausting as indecision, and nothing is so futile.

Change is one thing, progress is another.

Thinking you know when in fact you don't is a fatal mistake, to which we are all prone

Remote from human passions, remote even from the pitiful facts of nature, the generations have gradually created an ordered cosmos [mathematics], where pure thought can dwell in its natural home.

Americans need rest, but do not know it. I believe this to be a large part of the explanation of the crime wave in the United States.