The Door of Night

[Carannillion]

Elrian wrote:

Melkor would break himself free. Why break the master free only to become a servant again, when you can be the master? The Valar control the doors of night, Vingelot enters the sky through it, Sauron would likely be cast in himself if he tried to.

Perhaps Sauron's will was so tightly controlled by Melkor that everything Suron did - even creating the One Ring - was with an ultimate goal; to free Melkor again? Sauron could have been so blinded by his will to free his master that he thought he could beat the Valar...