The One Ring

[doug*platypus]

A fair question, for sure. The power of the Ring is discussed here among other places. It grows in power as it nears Orodruin, where it was forged (there's no place like home), and It also has the ability to influence someone who is not wearing It, which can be seen in particular in Frodo and Gollum. Also Bilbo, whose youthful vigour continues after the Ring has left him, but only up until It is destroyed.

It's very likely that once the Ring was near both himself and Mt. Doom, Sauron would be able to tap into its power and assume a bodily form again. He is probably only disembodied because he does not have all of his power, much of which is in the Ring.

I've been wanting to say this for a long time by the way: the Big Red Eye thing is really, really dumb. He's a terrible villain. Saruman, Shelob and Morgoth were all much scarier. So was Gollum. Sauron Schmauron.