Darkness

Darkness or the Dark and the Shadow is both the ever presence of evil in the universe which began with the rebellion of Melkor in his heart before Eä and The Void which is an absence of the light or the light of Ilúvatar. It is generally used to refer to the evil of Morgoth and Sauron over the ages.

History of Darkness
The rebellion of Melkor tampered with and poisoned the original perfect symmetry of Arda and corrupted all the works of the Ainur, but his chief works of darkness fell upon the hearts of the Children of Ilúvatar. After his decline and fall, his successor Sauron continued his works of evil until he to was defeated.

Darkness and Men
Of all the races in Arda, men were the easiest to corrupt and drive into temptation and thus were most afflicted by the darkness. Not long after they awoke, Morgoth, probably dressed as a black rider on a black steed convinced them to worship him as their god instead of Eru, but some escaped and repented becoming the Edain the descendants of the Dúnedain but most still remained in darkness. Those that did remain and never went West remained loyal to Morgoth became known as Easterlings and were ever allied with the dark powers throughout the long ages either for hope of conquest or plunder.

In the Second Age when the men of Numenor fell under the shadow, their faith wavered and their hearts turned ever to darkness. Then Sauron came and was soon the master of the king's council and men fell ever further into the shadow, convincing many of the faithless to worship Morgoth in the everlasting darkness beyond. Afterwards, darkness continued to compel men to follow its banner serving both themselves and Sauron even after his defeat in the War of the Ring.

Legacy of Darkness
Marring its original design, the advent darkness has brought the world its greatest woe but has brought many together who opposed it. As men whose hearts are forever tainted with the seeds of darkness brought down upon them by Morgoth and Sauron inherit the world after the Fourth Age, they may still have to face it again and again until the end of the world when all darkness is prophesized to be defeated.