Knowledge is of two kinds we know a subject ourselves, or we know where we can find information upon it.

It is my art. I am better at it than I ever was. And I will do it as long as I can. When you reach a certain age you can slough off what is unnecessary and concentrate on what is. And why not?

There are signs that the age of petroleum has passed its zenith. Adjusted for inflation, a barrel of crude oil now sells for three times its long-run average. The large western oil companies, which cartellised the industry for much of the 20th century, are now selling more oil than they find, and are thus in the throes of liquidation.