I'm guessing custom calligraphy by Hermann Zapf, who wrote the introduction.

- Lex

Why not lettering by Doyald?

Doyald hand drew the type on the cover, and has done the same for all his books. The letterforms are loosely based on Optima.

Well it is a font, now at any rate: http://doyaldyoung.com/113_YF_Roman/1131_Spec_YF_Roman/1131_Spec_YF_Roma...

It was the similarity to Zapf's Optima that made me say that.

- Lex

Yes, Young is a big admirer of Zapf, and this I think he acknowledges is a variation on Optima.

I've bought Young Finesse two years ago, and have used it for logotypes. It has a very nice touch. And of course all his books are to be recommended. In my eyes, Doyald is a fantastic designer and artist.