The Astral Tome is the source of most of the Astral Sorcery knowledge you will have access to. By right-clicking, the player can open the tome which will have several categories which unlock with progression. The tome's sections can be navigated by scrolling or dragging within the GUI, which will zoom in and out of them. Once zoomed in, the individual topics can be opened by clicking on them.
Holding Shift and right-clicking will open the Astral Tome's inventory, which is used to store Constellation Papers.