After waving his hand, Erik, Elora, Naeku, and Lemayian teleported to a room much akin to a library but filled with paper-sized slabs of some kind of mineral or metal.
This was the standard method of storing information in Söl and beyond. They carved letters and words in them using aetherium, but to fit all the information of a single book on these slabs, they made the letters so small, that they were impossible to read with the naked eye, even for the highest-ranking Arcanists.
So, these books were read with omnisense—which was also the reason why the books in the library of Erik's dimension were regular books, instead. After all, that dimension was supposed to have been inherited on the very first day of the awakening, when the Harbinger wouldn't have had omnisense yet.