‘Morgoth is thrust through the Door of Night into the outer dark beyond the Walls of the World, and a guard set for ever on that Door. The lies that he sowed in the hearts of Men and Elves do not die and cannot be slain by the Gods, but live on and bring much evil even to this day. Some say also that secretly Morgoth or his black shadow and spirit in spite of the Valar creeps back over the Walls of the World in the North and East and visits the world, others that this is Thu his great chief who escaped the Last Battle and dwells still in dark places, and perverts Men to his dreadful worship. When the world is much older, and the Gods weary, Morgoth will come back through the Door, and the last battle of all will be fought. Fionwe will fight Morgoth on the plain of Valinor, and the spirit of Turin shall be beside him; it shall be Turin who with his black sword will slay Morgoth, and thus the children of Hurin shall be avenged.’ (J.R.R. Tolkien, ‘The Shaping of Middle-Earth’, p. 47)
