Prediction is very difficult, especially about the future.
Never express yourself more clearly than you are able to think.
There are some things so serious you have to laugh at them.
No, no, you're not thinking; you're just being logical.
The opposite of a correct statement is a false statement. But the opposite of a profound truth may well be another profound truth.
Every great and deep difficulty bears in itself its own solution. It forces us to change our thinking in order to find it.
An expert is a man who has made all the mistakes which can be made, in a narrow field.