In our reasonings concerning matter of fact， there are all imaginable degrees of assurance， from the highest certainty to the lowest species of moral evidence.

如果你能看见，就看。如果你能看，就观察。

Success is not the key to happiness. Happiness is the key to success. If you love what you are doing, you will be successful.

I never buy anything unless I can give a good reason why I think it will go up.

The end of history will be a very sad time. The struggle for recognition, the willingness to risk one's life for a purely abstract goal, the worldwide ideological struggle that called forth daring, courage, imagination, and idealism, will be replaced by economic calculation, the endless solving of technical problems, environmental concerns, and the satisfaction of sophisticated consumer demands.

The greatest challenge to any thinker is stating the problem in a way that will allow a solution.