From an NYT interview with Christopher Hitchens on the occasion of the publication of his memoir Hitch-22:
Did you write the book for money?
Of course, I do everything for money. Dr. Johnson is correct when he says that only a fool writes for anything but money. It would be useful to keep a diary, but I don’t like writing unpaid. I don’t like writing checks without getting paid.
The fool in excelsis, I suppose, would be he who not only writes what cannot sell, but uses his own blood for ink. I am thinking of Nietzsche whose posthumous birth was due in no small measure to the auto-vivisection which supplied the fluid which powered his pen.