Tolkien at the End of Time; Alchemical Secrets of The Lord of the Rings
The Power of the One Ring
The chief power (of all the Rings alike) was the prevention or slowing of decay (i.e. 'change' viewed as a regrettable thing), the preservation of what is desired or loved, or its semblance. But also they enhanced the natural powers of a possessor thus approaching 'magic', a motive easily corruptible into evil, a lust for domination.'
The Three Rings of Power were brought forward into this world through the Elves innate powers of creative envisioning for the distinct purpose of preserving beauty in the world. These Rings did assist in the slowing of aging and deterioration, but unlike the One Ring, they did not confer the power of invisibility. At the same time, in the depths of the subterranean fire of his Evil Kingdom, Sauron secretly forged the One Ring that held within it the power of all the Rings. The One Ring gave him ultimate control over the other Rings, for it granted him the ability to read the thoughts of anyone who used them, influence their actions, and in the end bind them to his will. Due to the fact that Sauron had the one Ring he easily gained control over the minds and wills of the largest part of the Númenóreans, which led to the downfall of this first great Kingdom of Men.
The Power of the One Ring
The chief power (of all the Rings alike) was the prevention or slowing of decay (i.e. 'change' viewed as a regrettable thing), the preservation of what is desired or loved, or its semblance. But also they enhanced the natural powers of a possessor thus approaching 'magic', a motive easily corruptible into evil, a lust for domination.'
-J.R.R. Tolkien from the Preface to The Silmarillion