An expert is a man who has made all the mistakes which can be made, in a narrow field.
Truth is something that we can attempt to doubt, and then perhaps, after much exertion, discover that part of the doubt is not justified.
Predition is risky, especially of the future.
One must always do what one really cannot.
A deep truth is a truth so deep that not only is it true but it's exact opposite is also true.
Prediction is difficult, especially the future.