The Quenta Silmarillion is the longest part in the book, to which gives its title, and consists of more than twenty chapters. The saga deals with the history of Arda following the entrance of the Ainur as the Valar (see Ainulindalë).
In the fictional context of Middle-earth, the Quenta is sometimes assumed to be a part of and derived from Bilbo Baggins's Translations from the Elvish, which he composed from Pengolodh’s original source found in Rivendell, and became a part of the Red Book.
After the Valar's entrance, Arda was still lifeless and had no distinct geographical features. The initial shape of Arda, chosen by the Valar, was of a symmetrical continent lit by two lamps: one in the continent's north, and one in the south. However the lamps were destroyed by the vicious Melkor. Arda was again darkened, and the lamps' fall spoiled the perfect symmetry of Arda's surface. Two main continents were created that are of concern to the story: Aman on the far West, and Middle-earth to the East, over the Great Ocean.
Following this, Melkor hid himself from the Valar in an enormous fortress, Utumno. He also surrounded himself with horrible beasts, many of them Maiar in the form of fell animals, known as Balrogs. Balrogs were to remain his most faithful servants and soldiers ever after.
The Valar then made for themselves a home at the utmost West, upon Aman. Then the Valar began to reshape Arda yet again, making it habitable and preparing it for the coming of the Children of Ilúvatar: Elves and Men. However everywhere they went, Melkor followed them spoiling the fruit of their labour and damaging their achievements. Thus, all of Arda was marred by Melkor's anger, envy and lust of power.
Utumno did not protect Melkor, however. He was taken prisoner and sentenced to three ages (about 9,000 years) of imprisonment. Utumno was laid bare; but all its evil was not destroyed. Before Melkor was taken captive, Arda witnessed the Awakening of the Elves, the first-born Children of Ilùvatar. Elves are described as anthropomorphic beings, who, however, are immortal and possess many virtues (beauty, health, ability to communicate with nature), beyond the share of Men. The Elves were met by the Valar and invited to join them in the West; however Melkor managed to reach some of the Elves even earlier. It is said that from them he bred the hideous race of Orcs whom both he and his follower Sauron used as soldiers.
Some of the Elves refused to go westward. They became known as the Avari. Two houses of the Elves, the Vanyar and the Noldor crossed the Great Sea with the help of the Valar. A third house, called the Teleri lingered on the eastern shore of the Great Sea and in the west of Middle-earth. Eventually many of the Teleri crossed the Great Sea, but some Teleri remained in Middle Earth. The groups of Teleri that remained are termed Sindar, Nandor and Falathrim. (See: Sundering of the Elves).
There arose a mighty Elf among the house of Noldor, named Fëanor. Fëanor was skilled in crafts and his greatest achievement has been the making of three wonderful jewels, the Silmarils. The Silmarils contained the light of the Two Trees of Valinor.
By that time Melkor's captivity was over. However he returned to evil quickly. Through a vicious design he managed to destroy the Two Trees and to steal the Silmarils. Then he fled eastward, to the Middle-earth.
The furious Fëanor followed Melkor (whom he re-named Morgoth). This was done against the will of the Valar, and during Fëanor's flight he slew many of the Teleri, over their refusal to lend him their ships (First Kinslaying). For this he and his followers were forbidden to approach Aman ever again. However, Fëanor ignored this punishment and managed to cross the Great Ocean eastward. There he joined with the Sindar, who had been in Middle-earth all along. Years after this flight, in order to diminish the darkness, the Valar launched the Sun, so that it would dissolve Melkor's shadows.
Morgoth, having returned to Middle-earth, fortified his previous secondary fortress, Angband with its capital at Thangorodrim. From there he waged war upon the Sindar. However, with the help of the Noldor who had just crossed the Ocean, the first onslaught of Morgoth's attack was thrown off.
Following this, the Noldor settled with the Sindar in the West of Middle-earth, known as Beleriand. They adopted the Sindarin language instead of their native Quenya. This period of relative peace and stability was short-lived (at least by the Elves' standards). One of the first victims of this war was Fëanor himself. As time passed, Morgoth gathered more and more force.
Three hundred years after the coming of the Noldor to Beleriand, Middle-earth witnessed the awakening of Men, the Secondborn (or the Followers). Most of them allied with the Elves in order to defend Beleriand from Morgoth. However neither Elvish skill, nor Mannish resolve succeeded in defying him. One after another, the domains of Elves and Men were destroyed and filled with evil.
At last, more than five centuries after the flight of the Noldor, Eärendil, the son of an Elf-woman and a Man set sail to the West with the only Silmaril that his ancestors managed to recover. He was allowed to land in Aman, and to plead with the Valar for mercy towards the Elves and Men.
The Valar agreed to pardon the Noldor. They set out to fight Morgoth and were victorious. Morgoth was expelled from Arda. However during the conflict, the very continent of Beleriand was destroyed and sunk, thus forming a new shoreline for Middle-earth, hundreds of miles to the east.
The Valar offered Elves their forgiveness and the right to come to Aman. Many of them did indeed leave Middle-Earth, weary of centuries of warfare against the ever-growing evil. The tribes of Men that helped the Elves were given a whole island of their own, on which they founded the kingdom of Númenor.
Eärendil, because he possessed both mortal and immortal heritage, was given the opportunity to choose his fate; a gift that was also given to all of his descendants who were born of an immortal parent. His Silmaril became a bright star. One Silmaril was sunk in the water of the Great Ocean, and the third was lost in the depths of the Earth. Thus other than the sun and moon above, no trace remained on Middle-earth of the Two Trees of Valinor; but their influence lives on in the elements: air, water and fire/earth.
- Robert Foster, The Complete Guide to Middle-earth, entry "Translations from the Elvish"
- J.R.R. Tolkien, Christopher Tolkien (ed.), The Book of Lost Tales Part One, "Foreword", pp. 5-6
- J.R.R. Tolkien, Christopher Tolkien (ed.), Morgoth's Ring, "Part Three. The Later Quenta Silmarillion: (II) The Second Phase: The Valaquenta", p. 200