In that hour I looked on Aragorn and thought how great and terrible a Lord he might have become in the strength of his will, had he taken the Ring for himself. But nobler is his spirit than the understanding of Sauron, for is he not of the children of Lúthien ? Never shall that line fail, though the years lengthen
I like these sixty words because they are so full of the contradictions of Lord of the Rings. Aragorn is strong in will because he is descended from a Maia? Really? Like Isildur, who was tempted by the Ring and failed to become a Dark Lord only because of that lucky orc-arrow? Like Ar-Pharazôn the Golden, who rose against the Valar?
Clearly, being of the children of Lúthien is no guarantee. Sauron, who actually was a Maia, can't understand him.
Legolas, what you are saying here doesn't quite add up! But the really important thing is not that Aragorn is strong of will, or that his family will last forever, but that he made his own decision to forgo power. Which is something that Frodo and Sam probably understand better than Legolas, for all his immortality and princely elvishness.
As Diana Wynne Jones says : All power corrupts, but we need electricity. :-D