I recommend that you explore the area to the right of the entrance to the scriptorium, in the first place, because you will find the interactive row of books shown in the above screenshot. Examine the books and press the hidden button, thank to which you will unlock access to a hidden chamber. In here, you will find a hidden symbol, which will reward you with an additional Focus point. Apart from that, you can find here a ring (Memories of the Dead - Stonemason's Memory).
I recommend that you now explore the central part of the scriptorium, thanks to which you will find a Scroll Holder - 4G, an Ink Bottle - 3G and an Ancient Ingot - 17G. Go then towards the opposite corner in the scriptorium. Also here, you will find an interactive row of books and you will have to find a hidden switch. You can now walk into the [Underground Ruins - Library Towers].
Note - you can access the location with towers over the wooden beams above but, as for now, you will not profit from this. This pat, however, will come in handy later on into the game, along the path back to the exit.