So a human encountering the divine, as Muslims believe Muhammad did, to the rationalist, this is a matter not of fact but of wishful fiction, and like all of us, I like to think of myself as rational.

Yet whether you're a rationalist or a mystic, whether you think the words Muhammad heard that night came from inside himself or from outside, what's clear is that he did experience them, and that he did so with a force that would shatter his sense of himself and his world and transform this otherwise modest man into a radical advocate for social and economic justice.