The Nature of Middle-earth

The first ever publication of J. R. R. Tolkien’s final writings on Middle-earth, covering a wide-range of subjects, and the perfect next read for those who have enjoyed Unfinished Tales and the History of Middle-earth series and are hungry for more.
The Nature of Middle-earth will comprise numerous late (c. 1959-73) and previously unpublished writings by J.R.R. Tolkien on the “nature” of Middle-earth, in both chief senses of that word: both metaphysical and natural/historical.
For Tolkien fans, readers, and scholars interested in learning more about Tolkien’s own views on Middle-earth. It will appeal in particular to those readers who enjoyed Unfinished Tales, and some of the later volumes of the History of Middle-earth. Indeed, many of the texts to be included are closely associated with materials published in those places, and were sent to Hostetter, specifically, in photocopy by Christopher Tolkien for potential publication.
Much as Unfinished Tales forms an unofficial thirteenth volume of the History of Middle-earth, this new book will sit very nicely alongside as an unofficial 14th volume. Of particular note, given the impending Amazon series, are several texts detailing the lands, flora, and fauna of Númenor, and the lives of Númenóreans.
(from HarperCollins)