I know that every player approaches a puzzle with a different mindset, and that's why some solutions seem obvious to certain players, and stump others. That being said: The player knows here that the goal is to transport something from one book to another, and the game has taught the player that the only way to do that is via the magic bag. Personally, I played the game blind to puzzle solutions with each new version before I opened the TRS file to work on the translation (which would give hints I didn't want), and the first thing I tried in this scene was clicking on the magic bag. I'm not trying to look smart or anything, but for me it seemed the way to transport him. This is the first feedback that I have heard from a tester/player that the magic bag solution stumped or annoyed them. I would be interested to hear if anyone else had similar problems and/or feelings about this puzzle.