Minecraft wiki entry for Trading, associated text: This is one of the most important professions late-game, as it allows you to obtain almost every enchantment, including treasure enchantments, with the exception of Soul Speed. In addition, it buys paper, books, and ink sacs, all of which farmable, giving a good source of emeralds. This allows you to get perfect enchanted gear, although it requires a lot of XP to add the enchantments on an anvil. In addition, it takes a while before you get the enchantment you need for each villager. There is no need to level them up unless you need name tags, in which case level them up with the latest available trade.