Concerning the rings of power

The One Ring was a gold band with no jewels. The size of the Ring changed in order to fit its wearer. The Ring appeared to be completely plain with no markings, but when it was heated with fire an inscription was revealed on the outside and inside. The script was Elvish because fine lettering was required, but the language was the Black Speech. It read:

Ash nazg durbatulûk, ash nazg gimbatul
Ash nazg thrakatulûk agh burzum-ishi krimpatul.
One Ring to rule them all, One Ring to find them,
One Ring to bring them all and in the darkness bind them.

With the One Ring, Sauron could know and command the thoughts of those who wore the other Rings of Power, in effect making himself the Lord of the Rings. The other Rings were subject to the One Ring because they had been made by the Elves using knowledge and skills taught by Sauron, who had deceived them about his true identity. This was true even of the Three Rings, which Sauron had not touched.

Through the Nine Rings, Sauron enslaved the wills of the Men who bore them and they became the Ringwraiths, or Nazgul. The Dwarves who bore the Seven Rings resisted enslavement, but they became greedy and valued gold above all else. The Three Rings were hidden by the Elves when the One Ring was made, and they did not use them while Sauron had the One.

The powers of the other Rings were dependent on the One Ring. The destruction of the One Ring meant that the other Rings would lose their powers, and everything that had been made or sustained by them would fade.

In order to make the One Ring powerful enough to rule the others, Sauron had to put much of his own strength and will into it. When he wielded the One Ring, Sauron's power was enhanced. Separated from the One Ring - as he was when Isildur took it from him - Sauron was initially dealt a severe blow. But while the Ring still existed, Sauron maintained a connection with its power from afar and he was able to recover much of his former strength.

If the One Ring were destroyed, Sauron would also be destroyed because he would no longer have sufficient power to maintain his existence and he would be reduced to nothing more than a shadow. But the chances of the Ring being destroyed were extremely remote.

The One Ring could not be destroyed by ordinary means. It could not be harmed even if struck by a sledge-hammer or cast into a furnace. Dragon fire could destroy the lesser Rings of Power, but not even Ancalagon the Black could have destroyed the One Ring. The only way the One Ring could be destroyed was to throw it into the fires of Mount Doom where it had been forged.

But no one - not even Sauron - had the strength of will to purposefully destroy the Ring. Sauron could not conceive that anyone would even try. The One Ring had a powerful influence over anyone who bore it. Both Isildur and Frodo Baggins had the opportunity to destroy it and failed to do so, although Frodo at least made a valiant effort.

The Ring appeared to have a will of its own. It could leave its bearer in order to return to Sauron, to whom it was linked. The Ring slipped off Isildur's finger in the Gladden Fields and exposed him to the Orcs hunting him. It left Gollum too when its master Sauron was stirring again in Middle-earth. Frodo was tempted to put the Ring on in the presence of the Nazgul, and thereby expose himself and the Ring to them.

The temptation exerted by the Ring was great. Smeagol murdered his friend Deagol the minute he laid eyes on the Ring in order to obtain it, and when he later lost the Ring, he was desperate to retrieve it at all costs. Boromir tried to take the Ring from Frodo by force. Bilbo Baggins was remarkable in that he was able to give up the Ring after bearing it for 60 years, yet when he saw the Ring again years afterwards, he was immediately tempted by it. Even Gandalf feared he would not be able to resist the Ring's lure.

The Ring was utterly evil. Anyone who used it would eventually turn to evil in the end, even if they started out with good intentions. A person of great power might be able to wield the Ring, and possibly even use it to overthrow Sauron, but they too would succumb to its evil and would simply replace Sauron as Dark Lord.

Gandalf was probably the only person in Middle-earth at the end of the Third Age capable of using the Ring to supplant Sauron. Gandalf and Sauron were both Maiar spirits who had taken physical form and therefore were of equivalent stature. If Gandalf had the Ring that would give him an advantage, but the Ring's allegiance was ultimately to Sauron. Which of them would have prevailed in such a contest of wills is debatable, but the end result would be the same: the Ring would be the master in the end.

Others like Galadriel, Elrond, or Aragorn would probably not be able to best Sauron in a face-to-face confrontation while wielding the Ring. Aragorn, at least, would be compelled to surrender the Ring to Sauron immediately, as would any mortal. Galadriel envisioned herself as being capable of supplanting Sauron as a Dark Queen, but this may have been a delusion caused by the Ring.

However, one of them might have been able to use the Ring to increase their own power and attempt to challenge Sauron with military force. This is what Boromir envisioned that he would be able to do with the Ring.

"What could not a warrior do in this hour, a great leader? What could not Aragorn do? Or if he refuses, why not Boromir? The Ring would give me power of Command. How I would drive the hosts of Mordor, and all men would flock to my banner!"

Boromir strode up and down, speaking ever more loudly: Almost he seemed to have forgotten Frodo, while his talk dwelt on walls and weapons, and the mustering of men; and he drew plans for great alliances and glorious victories to be; and he cast down Mordor, and became himself a mighty king, benevolent and wise.
The Fellowship of the Ring: "The Breaking of the Fellowship," p. 414

Boromir was likely also deluded about his ability to wield the Ring. However, if anyone did manage to succeed in such a venture, he would not become a benevolent and wise king but a tyrant instead.

Lesser mortals could not control the Ring, but the Ring gave each bearer power according to his stature by enhancing his own natural abilities. Smeagol, for example, became a sneak and a thief, aided by sharpened senses and the Ring's power to turn its wearer invisible.

The Ring turned the person wearing it invisible by shifting him into the world of the Unseen. He could not be seen by ordinary eyes, except perhaps by a faint shadow in direct sunlight. But the Nazgul could see a person wearing the Ring, because they themselves walked in the Unseen world, and the wearer of the Ring could see the Nazgul in their true form, as Frodo did at Weathertop.

The Nazgul were drawn to the Ring, and Sauron was also able to sense it. Sauron became aware of Frodo when he wore the Ring first at Amon Hen and then at Mount Doom. Sam Gamgee felt Sauron seeking him when he used the Ring on the borders of Mordor.

The world changed, and a single moment of time was filled with an hour of thought. At once he was aware that hearing was sharpened while sight was dimmed... All things about him now were not dark but vague; while he himself was there in a grey hazy world, alone, like a small black solid rock and the Ring, weighing down his left hand, was like an orb of hot gold. He did not feel invisible at all, but horribly and uniquely visible; and he knew that somewhere an Eye was searching for him.
The Two Towers: "The Choices of Master Samwise," p. 343

Sam could also understand the Black Speech while wearing the Ring, which may have been an effect of being in the Wraith-world or a power conferred by the Ring.

Not everyone was rendered invisible by the Ring. Sauron wore the Ring during the War of the Last Alliance, yet presumably he was visible when Elendil and Gil-galad fought with him and when Isildur cut the Ring from his finger. Whether this was because Sauron was the Ring's creator and master or because of his nature as a Maia is not known. Tom Bombadil - an immortal being of indeterminate nature - also remained visible when he put on the Ring. Tom was also able to see Frodo when Frodo put on the Ring.

The Ring unnaturally prolonged the lives of mortals, so that as the years wore on they began to feel stretched out and unbearably weary. Smeagol was of Hobbit-kind with a natural lifespan of about 100 years, but with the Ring he lived to be nearly 600. Bilbo too had his life prolonged, and he appeared the same at age 111 as he had at 50. When Bilbo gave up the Ring he began to age visibly.

The Ring would eventually consume the mind of its bearer. Hobbits proved peculiarly resistant to its power, but they too were affected. Smeagol had only a small corner of his own mind left in the end. Even a good-natured Hobbit like Bilbo was driven to uncharacteristic anger when Gandalf tried to persuade him to give up the Ring. Frodo was so tormented by the burden of the Ring on his journey into Mordor that he never recovered and eventually had to leave Middle-earth in order to find peace.

If a mortal wore the Ring often, he would fade until he became permanently invisible. For eternity he would be trapped in the Wraith-world under Sauron's command, and he would be forced to surrender the Ring, which would break what remained of his mind.