People learn in different ways, and I remember reading, perhaps in [Pragmatic Thinking and Learning](https://pragprog.com/book/ahptl/pragmatic-thinking-and-learn...), that your tactile sense is as important for learning as your visual and aural senses, and so on.

I like the smell of books, too.

I doubt tactility (from a learning perspective) really comes into play while reading a book, as opposed to on a screen. That's not to denigrate paper book reading as an enjoyable experience, but let's not go overboard :)

The effect's subtle. I read Wycoff's Mindmapping in high school, and have tried the techniques off and on. One interesting idea is that you're constantly making background connections, and these can play a small but non-negligible association in the mind. So if you always chew a minty gum when doing your math work, it helps a bit in bootstrapping you back into that frame of mind later, like smelling bacon sizzling and feeling restful from associating it with family breakfasts.

Whether it works or not, well, I think it does, but it's no panacea. I prefer to think of it as a hint to start preloading a frame of mind (like the Jargon File's second use of 'swap' [0]). When I sit with a second hand book that's got that mild musty wood and glue smell, it gets me in the frame of mind to read. YMMV.

[0] https://www.catb.com/jargon/html/S/swap.html

For me it's a matter of quickly referencing material. For whatever reason, I seem to recall where things are roughly by the thickness of the stack of pages. The percentage bar on the Kindle doesn't replicate that. And flipping between pages on a device just takes too long. So, I have a hard time reading any sort of reference material on a Kindle.

Why not search for some keyword?

It's never as fast and document search on e-readers seems to be straight word match rather than any form of intelligent indexing. If I don't recall where something is, it's almost always faster to use the book's index than it is to naively search through the doc, in my experience.