Minecraft wiki entry for Things_not_to_do, associated text: To aid in efficiently using experience levels, the player should create means to have easy access to books and tools for enchanting. The player also needs bookshelves to gain access to high-level enchantments, something which is necessary to allow the player to not be forced to either spread low level enchants across cheap gear, put low level enchants on diamond armor and tools, or waste experience from going far past level 30 and possibly dying.