They say that smell is deeply linked to memory and books often have a particular smell too, whether it's from the paper or the ink or whatever. I wonder if that plays into it as well? I was going to say someone should study this but it appears many people already have: https://www.sciencedirect.com/science/article/pii/S1747938X1...

I find a similar effect from taking notes by hand - it reinforces the information much more strongly than typing. In college this was my major "hack" to get as much as possible out of my classes.