O anel único funcionaria para alguém além de Sauron?

The key quote from Tolkien that answers this is contained in Letter 246, with my added emphasis:

It was part of the essential deceit of the Ring to fill minds with imaginations of supreme power.

This implies that the Ring is useless to anyone but Sauron, but it tempts you into thinking it's a source of power, and in that way it gets you to wear it, and so gains control over you.

In order to proceed in an investigation of this, and how to reconcile it with other statements made by Tolkien we must first establish a baseline that we're going to work from:

• It is accepted that the Ring gave some degree of "power" to Isildur, Gollum, Bilbo, Frodo and Sam, in the form of invisibility, longevity and an occasionally enhanced presence.
• Sauron was the maker of the Ring; he originally made it for his own use, and his own use only; he certainly never intended it to be used by anybody else, and he had no requirement for any of these three (as he already possessed them due to his nature as a Maia).
• Therefore these three "powers" were not an intrinsic property of the Ring intended by it's maker, but rather efeitos colaterais of it being used by a mortal.
• And these "powers" are actually quite minor compared to those possessed by a Maia.
• There are different kinds of "power"; these minor (by comparison) "powers" are one kind that are available to mortals as Ring-bearers, but the power to raise armies, control others, defeat Sauron and rule Middle-earth is a completely different kind altogether.

Now let's look at what Tolkien says about the Ring, quoting from the same source as Shamshiel's answer:

But even if he did not wear it, that power existed and was in 'rapport' with himself: he was not 'diminished'. Unless some other seized it and became possessed of it. If that happened, the new possessor could (if sufficiently strong and heroic by nature) challenge Sauron, become master of all that he had learned or done since the making of the One Ring, and so overthrow him and usurp his place.

Here it's important to look at what Tolkien says, and apenas at what Tolkien says. Here's what he does não say (and note the emphasis):

• Some other person is controle the Ring.
• That other person is gaining power from the Ring.
• That other person is using that power against Sauron to defeat him.

And here's what he faz say (emphasis again):

• Some other person has claimed ownership of the Ring.
• That other person has, through their own "sufficiently strong and heroic" nature, succeeded in taking that ownership of it from Sauron.
• And Sauron as a result is diminished and can be defeated by the unenhanced other person (again, if "sufficiently strong and heroic").

This is an important but subtle distinction. In the first case the other person is using the Ring to give themselves a "level up" against Sauron, to boost their own power and defeat him that way -- but that's not what Tolkien is saying. In the second they're not doing this; the power in the Ring is quite useless to them but by being able to deny it to Sauron they diminish him and hence (though their own natural but unenhanced strength) are able to defeat him.

As for "become master of all that he had learned or done since the making of the One Ring" - Tolkien does not actually define what he means by this. But since the greater part of Sauron's power is in the Ring, it seems reasonable to suggest that this "mastery" actually belongs to the Ring itself rather than to the wielder (hence "since the making of the One Ring"), who only obtains the "mastery" by proxy.

But the Ring and all its works would have endured. It would have been the master in the end.

Now we'll continue by looking at some other sources. First of all, the words of Galadriel:

Before you could use that power you would need to become far stronger, and to train your will to the domination of others.

These seem to indicate that one could use the power of the Ring, but there are two traps being set for the careless reader here. The first one I've mentioned already:

It was part of the essential deceit of the Ring to fill minds with imaginations of supreme power.

And the second is mentioned elsewhere by Tolkien with reference to a different character in a different situation, but must surely also apply here:

Treebeard is a character in my story, not me...

So what we actually have here is Galadriel being enganado by the Ring into thinking it can be used, and remembering that she is a personagem in the story, not Tolkien himself, her words must only be read as being em personagem - they shouldn't be interpreted as Tolkien describing the way things are.

The same can be said of anyone else who describes using the Ring's power in a similar situation: Gandalf, Boromir, Denethor, even Elrond when he says "I will not take the Ring to wield it".

I'll round things off with some other observations, also from Letter 246. First of all Tolkien equates taking control of the Ring with the Ring taking control of you:

He needed time, much time, before he could control the Ring or (which in such a case is the same) before it could control him.

Then he establishes how difficult it is to face Sauron, even if you have tried to claim the Ring (and indicating that the Ring has no power over Sauron too):

Sauron would not have feared the Ring! It was his own and under his will.

And then he reiterates that the upper hand in a contest with Sauron does not come from your possession of the Ring, but rather from Sauron's lack of it:

On one side the true allegiance of the Ring to Sauron; on the other superior strength because Sauron was not actually in possession.

In summary - the answer is "no", the Ring não faria work for anyone else in the way they pensar it would (by granting them additional power or by being able to be used as a weapon), because remember:

It was part of the essential deceit of the Ring to fill minds with imaginations of supreme power.

But "yes", it seria work by causing Sauron to become diminished, provided they were strong enough to be able to take and retain control of it; they would remain limited to their own native ability in any contest against Sauron, however.

Yes. While the deceit of the ring was to offer imaginations of supremo power, it fez in fact, absolutely, one hundred percent, confer real power upon its wielder - just not supremo power, which not even Sauron possessed. The other answer is incorrect. There are examples of the Ring's powers - chiefly the domination of other wills, but also the understanding of "the thought behind speech" - being used in-story. And here is what Tolkien said:

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'. Unless some other seized it and became possessed of it. If that happened, the new possessor could (if sufficiently strong and heroic by nature) challenge Sauron, become master of all that he had learned or done since the making of the One Ring, and so overthrow him and usurp his place.

The reason we don't see the effects of the Ring all the time is threefold:

1. Because wielding the Ring takes effort and practice. "Before you could use that power you would need to become far stronger, and to train your will to the domination of others", in the words of Galadriel. In fact, she says that without this training, the Ring would destroy Frodo.
2. You have to actually claim the Ring as your own to truly use its power. Frodo and Bilbo never did this, and maybe Gollum just never had the strength. The moment Frodo claimed the Ring for his own, Sauron sabia. "And far away, even as Frodo put on the Ring and claimed it for his own, even in Sammath Naur the very heart of his realm, the Power in Barad-Dur was shaken, and the Tower trembled from its foundations to its proud and bitter crown. The Dark Lord was suddenly aware of him[...]
3. The power of the Ring is not absolute. Sauron was able to dominate and subvert the Numenoreans only with time and subtlety. And the reason Sauron had to do that? "So great was the might and splendour of the Númenóreans that Sauron’s own servants deserted him." So even Sauron wielding the Ring wasn't able to control his own servants under some circumstances.

Bilbo and Gollum are actually good examples of the power of the Ring: forcing a mortal to stay alive is tremendo. The Ring doesn't grant you courage, strength, wisdom, or magic spells. It gives you the power to dominate others, strengthens your native ability to read minds, and, if you're a mortal, forces you to stay alive - not even the Ring can fundamentally change fate decreed by Illuvatar; the Ring is already stretching The Rules quite a bit here.

The Ring granted Frodo and Sam it's chief power and purpose - domination over others - on several occasions, to subdue Gollum and to terrify Orcs. This was before Frodo even claimed the Ring.

Then suddenly, as before under the eaves of the Emyn Muil, Sam saw these two rivals with other vision. A crouching shape, scarcely more than the shadow of a living thing, a creature now wholly ruined and defeated, yet filled with a hideous lust and rage; and before it stood stern, untouchable now by pity, a figure robed in white, but at its breast it held a wheel of fire. Out of the fire there spoke a commanding voice.

‘Begone, and trouble me no more! If you touch me ever again, you shall be cast yourself into the Fire of Doom.’

The crouching shape backed away, terror in its blinking eyes, and yet at the same time insatiable desire.

Then the vision passed and Sam saw Frodo standing, hand on breast, his breath coming in great gasps, and Gollum at his feet, resting on his knees with his wide-splayed hands upon the ground.

Ou:

For what it saw was not a short frightened hobbit trying to hold a steady sword: it saw a great silent shape, cloaked in a grey shadow, looming against the wavering light behind; in one hand it held a sword, the very light of which was a bitter pain, the other was clutched at its breast, but held concealed some nameless menace of power and doom. For a moment the Orc crouched, and then with a hideous yelp of fear it turned and fled back as it had come.

We also have some examples of what seria have happened, from Tolkien's letters. For example, what if Gollum hadn't been there at Mount Doom?

Frodo too would then probably, if not attacked, have had to take the same way: cast himself with the Ring into the abyss. If not he would of course have completely failed. It is an interesting problem: how Sauron would have acted or the claimant have resisted. Sauron sent at once the Ringwraiths. They were naturally fully instructed, and in no way deceived as to the real lordship of the Ring. The wearer would not be invisible to them, but the reverse; and the more vulnerable to their weapons. But the situation was now different to that under Weathertop, where Frodo acted merely in fear and wished only to use (in vain) the Ring's subsidiary power of conferring invisibility. He had grown since then. Would they have been immune from its power if he claimed it as an instrument of command and domination? Not wholly. I do not think they could have attacked him with violence, nor laid hold upon him or taken him captive; they would have obeyed or feigned to obey any minor commands of his that did not interfere with their errand – laid upon them by Sauron, who still through their nine rings (which he held) had primary control of their wills. That errand was to remove Frodo from the Crack. Once he lost the power or opportunity to destroy the Ring, the end could not be in doubt – saving help from outside, which was hardly even remotely possible. Frodo had become a considerable person, but of a special kind: in spiritual enlargement rather than in increase of physical or mental power; his will was much stronger than it had been, but so far it had been exercised in resisting not using the Ring and with the object of destroying it. He needed time, much time, before he could control the Ring or (which in such a case is the same) before it could control him; before his will and arrogance could grow to a stature in which he could dominate other major hostile wills. Even so for a long time his acts and commands would still have to seem 'good' to him, to be for the benefit of others beside himself.

It also granted Sam the ability to understand the speech of Orcs, and Frodo was able to understand Galadriel's thoughts: "[Frodo] perceived my thought more clearly than many who are accounted wise."

However, in the end, the Ring - as essentially distilled Sauron and "power" - would have turned anyone who used it "evil." From Tolkien's letters:

In any case Elrond or Galadriel would have proceeded in the policy now adopted by Sauron: they would have built up an empire with great and absolutely subservient generals and armies and engines of war, until they could challenge Sauron and destroy him by force.

Confrontation of Sauron alone, unaided, self to self was not contemplated. One can imagine the scene in which Gandalf, say, was placed in such a position. It would be a delicate balance. On one side the true allegiance of the Ring to Sauron; on the other superior strength because Sauron was not actually in possession, and perhaps also because he was weakened by long corruption and expenditure of will in dominating inferiors. If Gandalf proved the victor, the result would have been for Sauron the same as the destruction of the Ring; for him it would have been destroyed, taken from him for ever. But the Ring and all its works would have endured. It would have been the master in the end.

Gandalf as Ring-Lord would have been far worse than Sauron. He would have remained ‘righteous’, but self-righteous. He would have continued to rule and order things for ‘good’, and the benefit of his subjects according to his wisdom (which was and would have remained great)."

EDIT: To clarify, the One Ring did enhance Sauron's powers as well, and it was not created solely to control the wielders of the other Great Rings.

From Tolkien's letters, the Ring was created in "his [Sauron's] effort (largely unsuccessful) to enslave the Elves, e in his desire to establish a control over the minds and wills of his servants."

Additionally, we know Sauron used the One Ring to subjugate the Numenoreans. From Letter 211:

He naturally had the One Ring, and so very soon dominated the minds and wills of most of the Númenóreans.

Thus, the Ring could be used by Sauron used to dominate the minds and wills of people who were não wearing other rings. Wielding another one of the Great Rings only seems to have made you especially vulnerable.

The reason we didn't see any amazing tricks from Frodo or Sam (beyond terrifying and subjugating Gollum, Orcs, etc.) is explained in the book, and in one of my quotes above. Frodo asks Galadriel why he can't use the Ring to know the thoughts of the wielders of the Three:

'Only thrice have you set the Ring upon your finger since you knew what you possessed. Do no try! It would destroy you. Did not Gandalf tell you the rings give power according to the measure of their possessor? Before you could use that power you would need to become far stronger, and train your will to the domination of others.'

Using the power of the Ring is not as simple as "put it on, get amazing results."

Yes -- the One Ring seems to "work" for beings other than Sauron, as Samshiel says. The relevant factor is not just possession of the Ring, but consciously tentando to use it to exert power over others. I think Gandalf remarked that the Ring granted Smeagol "power according to his stature" -- so all he could do was commit petty acts of evil, for which he was eventually cast out of his homeland.

As for the others, Frodo, Bilbo and Sam seldom or never used the One Ring in this way. Isildur is an interesting case. The power of the Ring poder have helped him make Gondor stronger than it would otherwise have been, by eliminating any remaining enemies. He was ambushed and killed before he could do the same in Arnor, which may be one reason why Gondor endured while Arnor collapsed into civil war and ruin. On the other hand, Isildur was already an exceptionally capable individual, unchallenged as King, and most of his enemies had been destroyed or scattered at the Battle of the Last Alliance, so he may not have necessário much assistance from the Ring.

I think that power proportionate to the wielder's own strength is the key point. So Smeagol only had petty abilities. Someone like Aragorn or Boromir might have become a great and merciless conqueror, much like Genghis Khan with added longevity. (He might end up like the Witch-King of Angmar, only more powerful and not owing allegiance to any other being.) Finally, a being like Gandalf, Saruman or Galadriel might have become a godlike figure, as powerful as Sauron himself or even more so.

I can see how Gandalf might have been even more terrifying than Sauron, if he was corrupted by the Ring. Sauron doesn't care if his subjects argue among themselves, drink beer, play games, or whatever as long as they obey his commands. Gandalf the Ringlord would not allow that kind of disorderly behaviour. Arguing, fighting, eating too much cake, or ignoring a "do not walk on the grass" sign would incur dire punishment. Recreation would mean gathering to sing songs in praise of Gandalf's benevolent rule.

To bolster the answer of Sim already stated by other answers, we do see that Frodo was granted the power to percieve the other Rings of Power. Specifically, he was able to see Galadriel's ring:

'Yes', she said, divining his though, 'it is not permitted to speak of it, and Elrond could not do so. But it cannot be hidden from the Ring-bearer, and one who has seen the Eye. Verily it is in the land of Lorien upon the finger of Galadriel that one of the Three remains. This is Nenya, the Ring of Adamant, and I am it's keeper.'

This is more of a supplementary answer because I don't want to repeat what was mentioned in the answers already.

Short answer: No, it only works for Sauron; because it only gives him the advantages; it doesn't give anyone else any advantages of using it.

Long answer: We really never seen any examples of Sauron himself being augmented with powers due to the ring. For example, Sauron might have had superior strength but compared to what? Before the ring? We were never given any comparisons of his strength. In fact, there is no mention of him using the ring for any other purpose than to control the other rings. He was probably just as strong as he was before together WITH IT; but once he's separated, Sauron would be weaker than ever before.

Before I continue, I'll pose a question, how does the ring make him (or anyone) else more powerful? He basically just transferred his native power into it; but that's it. He simply transferred energy, not augment it. When we transfer something, we mean we displace "something" from one container.. to another; what this means is that the transfer has weakened Sauron himself.. but the ring's purpose has been empowered; this is proven by the fact that when he was departed from the ring, it exposed his true weakened state and had to go into hiding.

Power is really all about perspective here. Like what does it mean to be truly powerful?

To discuss the meaning of absolute power we could suggest the following:

• There should not be any need for any defense mechanisms, such as the power to vanish since there's nothing to hide or run away from. We could argue that vanishing doesn't mean it's a defense mechanism, but we could still argue the point on having it as a feature.
  • However, all examples of reasons why someone would vanish is to hide and protect themselves from being discovered. When we talk about concealing, we do not think about the context of power here.
• There should not be a need to create these "ring satellites" and deceive the other races of men, dwarves, and elves into wearing them so that they'd be manipulated and controlled. The ring would enable Sauron to force any race into submitting to his will. The ring would be powerful enough by itself to get Sauron what he needed.
  • Sauron had to DISGUISE himself as "Annatar" the "lord of gifts", into creating rings to control them.
• It would be impossible for the ring to be separated from the master, there would be no weak points in it.
  • Sauron was separated from the ring by a single slash of a sword cutting his finger off, no thanks to Isildur

So with all these points in mind, we could suggest that the ring really serves one purpose, that is to deceive and weaken the enemies of Sauron, which would then allow Sauron to take advantage over them. It would NOT weaken all enemies, just the ones connected with the ring.

Examples: The vanishing feature, though used as a defense mechanism for the ring bearer, it doesn't augment their power.. but it does give Sauron an advantage to discovering the vicinity of their location.

Being possessed, puts them at a disadvantage from being discovered as they are walking into enemy territory, risking themselves in getting caught or captured.

Both answers so far have overlooked that old Tom Bombadil was unaffected by the ring when he put it on his finger. Yes, some beings (of stronger magic) would be able to take control as Gandalf and Galadriel described.

I think they were right about its corruptive abilities as well. Both would have been subject to the corruption from it through the rings that they already wore, and they had seen what became of the individuals who put on that one ring.

You actually asked a series of questions.

It appears though that you have three main questions.

1) "Would the One Ring even work for anyone but Sauron?"

2)"But does the One Ring actually convey power to anyone but Sauron?"

3) "Do we ever see any actual, "positive" effects from possessing the One Ring?"

I'm not sure what you mean by "work". A person can wear it. It does stuff to them, it gives them some powers(ie; invisibility, long life, etc.). Positive effects? It'd be pretty cool to be invisible when you want. I'd like to live to see 500. So it works and it does convey power. Some of those powers are positive. So the answer is yes, yes, and yes.

I'm not going to get into the nitty gritty of other people's answers. However, here is a power it granted that has not been mentioned previously. It answers all three of your questions. This power "works" for Frodo not just Sauron, "coveys" Frodo power, and it's a positive effect. It gave Frodo the ability to see much further than a person not wearing the ring from the seat of seeing.

"At first he could see little. He seemed to be in a world of mist in which there were only shadows: the Ring was upon him. Then here and there the mist gave way and he saw many visions: small and clear as if they were under his eyes upon a table, and yet remote. There was no sound, only bright living images. The world seemed to have shrunk and fallen silent. He was sitting upon the Seat of Seeing, on Amon Hen, the Hill of the Eye of the Men of Númenor...And suddenly he felt the Eye. There was an eye in the Dark Tower that did not sleep. He knew that it had become aware of his gaze. A fierce eager will was there. It leaped towards him; almost like a finger he felt it, searching for him. Very soon it would nail him down, know just exactly where he was. Amon Lhaw it touched. It glanced upon Tol Brandir he threw himself from the seat, crouching, covering his head with his grey hood."

I didn't put the entire quote as it's quite long, but the three periods I installed were a description of just about everything going on in middle earth at the time. The ring conveyed him so much sight that he could see all the way to mordor and see Sauron himself. The sight was so strong that Sauron himself felt the gaze of Frodo. So the ring did have extraordinarily enhancing features.

After Aragorn goes onto the seat of seeing.

"Aragorn hesitated. He desired to go to the high seat himself, hoping to see there something that would guide him in his perplexities; but time was pressing. Suddenly he leaped forward, and ran to the summit, across the great flag-stones, and up the steps. Then sitting in the high seat he looked out. But the sun seemed darkened, and the world dim and remote. He turned from the North back again to North, and saw nothing save the distant hills, unless it were that far away he could see again a great bird like an eagle high in the air, descending slowly in wide circles down towards the earth."

Aragorn saw hardly anything.

Christopher Tolken gave a lengthy discussion of the various drafts of Lord of the Rings and explains a difference in the final draft.

"... this is associated with the fact that in the final form Aragorn does go up but sees nothing it may suggest a more complex relation between the power of Amon Hen and the power of the Ring... [The Departure of Boromir, HoME 7]"

I'm not going to do a lengthy research paper for each of the rings powers, when they showed themselves, how it was used, etc. That's the point of reading the books. Others have given multiple examples of this, I just wanted to add one that was left out, and (breakdown) answer the actual original question.

I'm not sure why everyone's being so philosophical, the ring works just fine on Frodo.

How so? Let's recall what the ring does by reading the User's Manual, conveniently printed on the inside of the ring itself:

One ring to rule them all, one ring to find them,

One ring to bring them all, and in the darkness bind them

Assim,

1. Bring them all: Frodo is certainly found by/finds/happens upon a whole bunch of ring bearers - most of the human rings and all of the Elven ones. As for the Dwarf rings, well, that feature was broken to begin with and didn't work for Mairon either. Assim, [✔].
2. Encontrá-los: When Frodo puts the ring on, I recall he is very noticeable to other rings bearers (at least, the Human rings), and vice versa. See also this detailed answer. Now, probably a more experienced/corrupted/powerful bearer of the one ring would be better with this perceptive skill, but I'll put this one down as [✔].
3. Bind them: The Elven rings avoided the binding by design, and the Dwarven rings just didn't have that effect like Mairon wanted to, so it's basically the Human rings. Given that 'to rule them' is a separate point than the 'binding', you could claim that they're still bound to the ring, and in many senses to whoever it is that's wearing it, even if he's not ruling them. So, [sort-of-✔].
4. Rule them: This is the point about which everybody's fussing. Now, ok, maybe you don't get to boss (non-)people around that easily, and maybe you need to be a powerful Maia for that to actually work. So, [✖].

Three out of Four is pretty good, considering how Frodo is not really the ruling type. It's not clear why anyone should expect the ring to do other things for him.

Why do we assume that the ring benefitted Sauron at all? Every person who had it became obsessed with it and had to acquire it at all costs. They also seemed to suffer from the delusion that it possessed "great power" beyond invisibility. It seems reasonable to assume Sauron was affected too, and that's why he wanted it so badly - much the same way as Gollum did. After all, everything we know about him is supposition from the other characters. Gandalf saw Sauron's forces desperately trying to recover the ring and ASSUMED it had great magical power (or why else would he be trying to recover it), but it fact it was just a cursed "Addiction Ring" tied to Sauron's life force.

There is one thing missing in this discussion as it concerns Gandalf's real stature. Gandalf is also one of the Ainur. He is Maiar (lesser of the Ainur) and was sent to middle earth with the other Istari (wizards) by Manwe. They Istari did so but in a diminished form which apparently included lack of full awareness of who they really were. Regardless, when considering the effects of the ring on its wearer, Gandalf should not be grouped with Galadriel, Elrond or any others. The ring would perhaps of "unlocked" his full nature and I suspect he would have been less affected by its corrupting nature. Gandalf in this condition would likely have been able to directly challenge Sauron 1:1 and overthrown him. For elves and men the ring would have corrupted and betrayed them and I do not think they could have mastered the ring. Saruman (also Maiar like Sauron) probably understood this in his bones and his own corruption was likely due to visions of possessing the ring and being able to "fix" middle-earth for the better.

Unfinished Tales Part Four Chapter II 'The Istari' pp. 508–509

To the question: Sim. Additionally...

1) The One Ring has awareness and a personality and seduces the wearer into doing its bidding. For an inanimate object, that's a lot.

2) Power to control other powers is power. The brain is not very powerful outside the body.

3) It seems the great power of the One Ring is to cast illusions which it uses to both seduce and empower its bearer. As advertisers can attest, this is not an insignificant power.

Sim.

De acordo com a esta resposta Gollum possessed the ring for nearly 500 years while the average Hobbit lifespan is 96 years.

when Precious goes we’ll die, yes, die into the dust.

The One Ring will help you stay alive, ao controlee dominar as long as it can return to Sauron in the end.

In unfinished tales it says if Gandalf wielded the ring against Sauron,ultimately it would lead to Saurons destruction despite the rings allegiance to Sauron,

The origin of the story is the concept of the pukelman (actually the image of a pukelman). By creating the pukelman, the owner or artist transfers personal power and becomes at the same time more powerful by extending his abilities, but also more vulnerable. The pukelman(statue) appears for a few seconds in O Retorno do Reie muito mais O Silmarillion. The ring is Sauron's pukelman.

All of Tolkien's stories re-tell plots from ancient Scandinavian German origin. It is the giant and the egg, etc., etc.

Let's compare the ring, or, better, the palantir, with a computer in a post-apocalyptic world. The 'new user' can use the computer to make light in the dark or use it like a mirror. But they cannot find the Wikipedia database nor start the launch sequence of the missiles.

Such is the ring - in a network it would develop its full power of Administrator, as a standalone it is a nice tablestand.

I believe it is a reasonable assumption that because Sauron is a servant of Morgoth/Melkore, the ring would have worked for them and possibly sought him if he had still been a factor.

Sauron and his master, Morgoth, were a dichotomy of darkness: Morgoth corrupted nature, and Sauron exploited the corruption. Without Morgoth, Sauron was nothing, but once the world had been made with Morgoth embedded in it, Sauron had ample opportunity. All living beings, being made of the matter/cosmic data that Morgoth infected, had a hint of corruption, and were fodder for Sauron's exploitation in specific circumstances. The forging of the rings of power was a scheme by which Sauron could create these circumstances more easily. Witness, for example, the greed of the dwarves. Ownership of the ring kept by Thorin's house was a mark of rulership for his clan. The dwarven rings increased the greed of dwarf kings, which in turn led them to drive their subjects harder and more recklessly. Presumably, the One's rulership over the other rings allowed Sauron to change their power levels, corrupting those who had them with greed or else making them over-reliant on the rings' power, and thus reliant on Sauron. Sauron was a power player, setting up his dopes like pieces on a chess board, and then activating them with one master stroke. They would relate to each other in predictable ways, weakening each other and strengthening him, and when all was said and done he'd be the winner. His only weakness was that he often interfered with forces that were beyond his ken, particularly Illuvatar. After the raid on Valinor, the powerful in Middle Earth became deathly fearful of his potential, forcing him to resort to brute force and sorcery.

According to Gandalf, one who is wise and mighty, like a wizard or Eldar, could, but the ring would still work against them. A more powerful being ( like Morgoth,could but Morgoth wouldn’t bother as it would be little to him ) . Eru could but would have no use of it. Saruman wanted it for good reason.