Among people I have met, the few whom I would term great all share a kind of unquestioned, fierce dedication; an utter lack of doubt about the value of their activities (or at least an internal impulse that drives through any such angst); and above all, a capacity to work (or at least to be mentally alert for unexpected insights) at every available moment of every day of their lives.

The Lying Stones of Marrakech (ed. Harvard University Press, 2011) - ISBN: 9780674061675