I have long wondered about the fact that Sauron and Saruman both started out as Maiar of Aulė. A while back it occurred to me that perhaps the issue that lead both of them, as well as Melkor and Aulė himself, into trouble (and why there was so much conflict between those two Valar) is one of materialism. Not necessarily materialism as we think of it (although heaven knows it was a failing of Melkor's) but rather that both Aulė and Melkor dealt heavily with the very material aspects of Arda. A love for the substances of the incarnate world can, in the right (or wrong) kind of mind be all too easily twisted into a lust. Aulė loved those things so much he strayed into error because he wanted to teach the incarnate Children before it was time for them to awaken; in Melkor and the others, it became a desire to control/own the incarnate world. Obviously, most of Aulė's people avoid that failing, but one might suppose that they are familiar with the desire. Thus it may have made perfectly good sense to send one of his Maiar as an Istar, presuming that they may have better insight into the workings of Sauron's mind though I would've been leery about letting someone who was so eager to go have the job. (I feel the same way about a lot of politicians.
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