The ever-current Edward Gibbons.

Over on National Review Online's "The Corner" Mark Styn, whose book
America Alone: The End of the World as We Know It is under legal attack in Canada for insulting Islam (or something like that) resorts to the great Edward Gibbon's Decline and Fall of the Roman Empire, as all educated pundits ought. The key quote is from Gibbon's description of the Battle of Poitiers (aka The Battle of Tours). Gibbon takes a short flight of fancy that Styn thinks is now coming true:

“Perhaps,” wrote Edward Gibbon in The Decline And Fall Of The Roman Empire, “the interpretation of the Koran would now be taught in the schools of Oxford, and her pulpits might demonstrate to a circumcised people the sanctity and truth of the revelation of Mahomet.”

You should read the whole thing though. Gibbon I mean. Not Styn. The latter seems a bit overheated (just check out the subtitle of his book).