> Now, how do I lend you a book for which I have no dead-tree copy? I can't give you such a piece of dead-tree (and naturally lose it for myself).

Why can't you lend it to me on the good faith I'll return to it you when I'm done?

Edit: Aha, I misread your comment! I think because in the proceeding paragraph you mention the case of having a dead-tree book but preferring e-ink. Of course, if you don't have it you can't lend it (assuming DRM prevents you).