Why take a body? Why make a Ring?

[Rune Son of Bjarne]

Originally Posted by littlemanpoet

I suppose it doesn't really matter: Melian chose to become incarnate so that she could love Thingol and have union with him, and give birth to Luthien and raise her, and set a destiny for Elves and Humans that none but Eru foresaw. Is this not subcreation for the purpose of enjoyment and sharing? But is it not more? ...because there's something of destiny in this now, which suggests something more powerful than mere enjoyment or sharing; but what?

That could not really be why she chose to become incarnated unless she knew all this would happen in advance. Why did she chose to walk in a earthly body in the forrest when Thingol came by? Surely she did not expect him to show up, then again she is a powerful Maia. . .Maybe she had forseen some of what would happen.