Precisely, the Istari were not sent by the valar to defeat Sauron, but to aid the peoples of middle earth in their struggle against him. They were there to show them what they were really capable of and to persuade them to stand up against him.
I think the reason for this is because the Valar had remoed themseles, and their lands, from Middle-earth, and did therefore not want to interfere too much in its affairs. However, they did not want it to be ruined and ruled by a second dark lord, so they sent the istari down as emmiseries to show them the way.
Curulin
__________________
Well, I'm back.
|