If you want to be successful, you have to be willing to fail.

The merit of Marx is that he suddenly produces a qualitative change in the history of social thought. He interprets history, understands its dynamic, predicts the future, but in addition to predicting it, he expresses a revolutionary concept: the world must not only be interpreted, it must be transformed.

A method of solution is perfect if we can foresee from the start, and even prove, that following that method we shall attain our aim.

Believe nothing you hear， and only one half that you see.