The Silmarillion

Now to water had that Ainu whom the Elves call Ulmo turned his thought, and of all most deeply was he instructed by Ilúvatar in music. But of the airs and winds Manwë most had pondered, who is the noblest of the Ainur. Of the fabric of Earth had Aulë thought, to whom Ilúvatar had given skill and knowledge scarce less than to Melkor; but the delight

And thou, Melkor, shalt see that no theme may be played that hath not its uttermost source in me, nor can any alter the music in my despite. For he that attempteth this shall prove but mine instrument in the devising of things more wonderful, which he himself hath not imagined.’

Of all the Great Ones who dwell in this world the Elves hold Varda most in reverence and love. Elbereth they name her, and they call upon her name out of the shadows of Middle-earth, and uplift it in song at the rising of the stars.

She goes rather to the halls of Mandos, which are near to her own; and all those who wait in Mandos cry to her, for she brings strength to the spirit and turns sorrow to wisdom.

He is the Doomsman of the Valar; but he pronounces his dooms and his judgements only at the bidding of Manwë. Vairë the Weaver is his spouse, who weaves all things that have ever been in Time into her storied webs, and the halls of Mandos that ever widen as the ages pass are clothed with them.

Therefore when they beheld them, the more did they love them, being things other than themselves, strange and free, wherein they saw the mind of Ilúvatar reflected anew, and learned yet a little more of his wisdom, which otherwise had been hidden even from the Ainur.

But Ilúvatar sat and hearkened until it seemed that about his throne there was a raging storm, as of dark waters that made war one upon another in an endless wrath that would not be assuaged.

And thou, Melkor, wilt discover all the secret thoughts of thy mind, and wilt perceive that they are but a part of the whole and tributary to its glory.’

But to achieve this he had been obliged to let a great part of his own inherent power (a frequent and very significant motive in myth and fairy-story) pass into the One Ring. While he wore it, his power on earth was actually enhanced. But even if he did not wear it, that power existed and was in ‘rapport’ with himself: he was not ‘diminished’.