Scraps of History
Herodotus is the guy who invented history. So it's fitting that, through Herodotus' book, the English patient reveals his own history.
Almásy keeps this book with him everywhere he goes, a fat volume that could explode at any moment like George Costanza's wallet. But unlike George's wallet, which is filled with junk he'll never use, Almásy's book is filled with keepsakes… which are rare bits of sentimentality from this man.
Ironically, he connects with Katharine when she tells a tale from Herodotus around the campfire—and the book isn't even in the scene. These guys have the Herodotus love connection. But later, when Katharine makes copies of the cave paintings in the Cave of Swimmers, she gives them to Almásy to paste in his scrapbook.
Almásy leaves the book with Katharine in the Cave at the end of the movie, and she writes in it as she dies. This allows Almásy to know Katharine's last words, even though he isn't there with her. It is these final words that Hana reads to Almásy as he dies:
"We die rich with lovers and tribes, tastes we have swallowed, bodies we have entered and swum up like rivers, fears we've hidden in like this wretched cave. I want all this marked on my body. We are the real counties— not the boundaries drawn on maps, the names of powerful men. I know you'll come and carry me out into the Palace of Winds. That's what I've wanted: to walk in such a place with you, with friends. An earth without maps. The lamp's gone out, and I'm writing in the darkness."
The book shows literature and history's power to repair. This happens quite literally in one scene, where Hana uses miscellaneous books from the library to repair the stairs. Without books—the Herodotus book in particular—the gaps between the characters would be unable to bridge.