THE NATURE OF MIDDLE-EARTH

JR.R. Tolkien regarded The Silmarillion as the foundation of his imagined world, but despite it being the primary, central work he was unable to bring it to a final form, and it was left to his son, Christopher, to construct the last version of a "Silmarillion" from the narratives that existed at the time of his father's death. For, having once been an enclosed myth, with a beginning and an end, it now had a vast extension, and within this there were major figures who had come out of the Elder Days, chief among them Galadriel, so a great deal of "writing back" would have to be done so that The Silmarillion could stand in relation to The Lord of the Rings.
The writings collected in The Nature of Middle-earth reveal the paths that Tolkien took as he sought to better understand his own unique creation, with greater precision, fullness and consistency. Varying in both scope and subject, they include : the operation of time and ageing among both the immortal and mortal peoples of Middle-earth, and the surprising degree of mathematical precision and skill Tolkien brought to bear to achieve rigour in this matter ; such foundational matters as creation, life, fate and free will, the nature and relationship of bodies and spirits, of authority, and purpose, and death ; vivid descriptions of the land, beasts, and peoples of Númenor ; the appearance of various characters in The Lord of the Rings, including which did or did not have beards.
All these writings reveal hitherto unguessed ideas and details of Tolkien's thought, imagination, and subcreation that are variously surprising, profound, and even charming.