Concern for man and his fate must always form the chief interest of all technical endeavors. Never forget this in the midst of your diagrams and equations.
Before you can inspire with emotion, you must be swamped with it yourself. Before you can move their tears, your own must flow. To convince them, you must yourself, believe.
That which is impenetrable to us really exists. Behind the secrets of nature remains something subtle, intangible, and inexplicable. Veneration for this force beyond anything that we can comprehend is my religion.
It would be possible to describe everything scientifically, but it would make no sense; it would be without meaning, as if you described a Beethoven symphony as a variation of wave pressure.
People in their handlings of affairs often fail when they are about to succeed. If one remains as careful at the end as he was at the beginning, there will be no failure.
Whoever wishes to foresee the future must consult the past; for human events ever resemble those of preceding times. This arises from the fact that they are produced by men who ever have been, and ever shall be, animated by the same passions, and thus they necessarily have the same results.
Four years ago, I promised to end the war in Iraq. We did. I promised to refocus on the terrorists who actually attacked us on 9/11. We have. We've blunted the Taliban's momentum in Afghanistan, and in 2014, our longest war will be over. A new tower rises above the New York skyline, al Qaeda is on the path to defeat, and Osama bin Laden is dead.
The purpose of life is not to be happy. It is to be useful, to be honorable, to be compassionate, to have it make some difference that you have lived and lived well.