This book should really be unnecessary. We prefer that all players here read the books by J.R.R. Tolkien on which the MUSH is based. Read "The Hobbit" first. Even though it is a children's book it is important. Read "The Lord of the Rings" afterwards and you will not have a lot of trouble understanding the universe we are trying to create here. But if you haven't read them, this summary will help you a little bit. Not nearly as much as reading the books would, though! Keep in mind that it is written from the viewpoint of elves, also.
For advanced knowledge, read The Silmarillion and the Unfinished Tales. If you become a real devotee, most of the draft versions and ideas for Tolkien's major works have also been published in the last couple of decades.
Dwarves