that with Tolkien, the condition of the heart has more to do with
susceptibility to the Ring than mere contact with it. In other words, the pure
of heart could hold out against it with a minimum of struggle, while those
compromised in some way (pride being the most dangerous quality, apparently)
succumb much more easily.
The Humble:
Bilbo/Frodo/Sam - Humble, non-ambitious. Were able to carry the Ring, sometimes
for years, with relatively little effect. Even Gollum may be an example of
this, as he carried it for 500 years or so without larger ambitions than
revenge on enemies and fissh every day.
The Noble: Elrond, Aragorn, Faramir, Gandalf - Each of these characters had the
opportunity to take the Ring, but refused it and the power it offered.
Galadriel, having hungered for power in her life, had the hardest time
resisting. Her decision to do so may have allowed her to return to Valinor
(depending on your favorite version of her story).
The Proud:
Boromir, Denethor, Saruman - Each of these wanted the Ring for his own ends,
being sure that he could control it and not be controlled. Only Boromir came
within reach of it, and he perished in the attempt to redeemd himself. I should
add to this category Isildur, who was clearly a noble Man, but whose pride
prompted him to claim the Ring as a weregild, against the advice of
Elrond.
Silverlode
"They looked as he pointed, and before them they could see the stream leaping down to the trough of the valley, and then running on and away into the lower lands, until it was lost in a golden haze."