Like a flash of lightning and in an instant the truth was revealed. I drew with a stick on the sand the diagrams of my motor. A thousand secrets of nature which I might have stumbled upon accidentally I would have given for that one which I had wrestled from her against all odds and at the peril of my existence.
You either choose this method of passing the evening because you are in each other's confidence, and have secret affairs to discuss, or because you are conscious that your figures appear to the greatest advantage in walking;— if the first, I should be completely in your way, and if the second, I can admire you much better as I sit by the fire.
For the secret of man's being is not only to live but to have something to live for. Without a stable conception of the object of life, man would not consent to go on living, and would rather destroy himself than remain on earth, though he had bread in abundance.
If the genius of invention were to reveal to-morrow the secret of immortality, of eternal beauty and youth, for which all humanity is aching, the same inexorable agents which prevent a mass from changing suddenly its velocity would likewise resist the force of the new knowledge until time gradually modifies human thought.
Science ... looks skeptically at all claims to knowledge, old and new. It teaches not blind obedience to those in authority but to vigorous debate, and in many respects that's the secret of its success.