So can the guy really not decide which is better, the scroll or the codex, as Erik Kwakkel suggests in his Tweet of this illustration? I doubt it. I expect Book A was a scroll and Book B a codex, and the enquiring philosopher needed to consult both.
Just so, nowadays e-book or print book are not mutually exclusive categories. We don’t have to (and nor do we) chose one or the other. We often use both, just as today I’m reading The Secret Agent in the handsome hardback CUP edition, but while on the subway I pick up the story on my iPhone’s Kindle app.