Tolkien: evil doing the good, which good could not do
Then, during a rest from pursuit by orcs, while Frodo sleeps, Sam looks up to see far above the murk "a white star twinkle." Smitten by its beauty he understands that "in the end the Shadow was only a small and passing thing: there was light and high beauty for ever beyond its reach." This is far more than the sighting of the physical beaming of a star. It is a spiritual vision of beauty and permanence which Sauron and his passing vileness can never stain. It puts everything into right perspective for Sam and gives him peace: "Now, for a moment, his own fate, and even his master's, ceased to trouble him." The world is in abler hands than his. A less visionary kind of help is sent later on the very slopes of Mount Doom when Sam has to carry Frodo and finds the burden light, "whether because Frodo was so worn by his long pains...or because some gift of final strength was given..." Tolkien guards the secular alternative but his favor is pretty clearly for the religious one. Finally, of course, as Frodo succumbs to the Ring at the Cracks of Doom, Gollum, playing out the role for which he has been preserved all through the epic, bites off Frodo's Ring-finger, overbalances (by no accident), and falls with the Ring into the flames below. The irony of evil is consummated by its doing the good which good could not do.
~~Paul Kocher, Master of Middle Earth, page 48.