Tolkien depicted an intricate series of dualities: characters who are faced with the same choices, but who react differently; Frodo and Bilbo; Bilbo and Smeagol; Smeagol and Samwise; Gandalf and Saruman; Boromir and Faramir.
It’s, in fact, quite explicit in the ‘nine walkers’ set against the ‘nine riders.’
Indeed, all one needs is an ‘r’ to make the name ‘Denethor’ out of the letters of the name ‘Theoden,’ both of whom are faced with the same circumstances and choices: despair at, first, the death of a son and, second, the wily importunings of an evil perspective; the wicked tongue in service to Saruman, in the case of Theoden and the deceitful use of the palantir by Sauron in the case of Denethor; in answer to these despairs, the one (Theoden) grasps life and the other (Denethor) chases death.
Bombadil is the one side of the duality that includes Sauron upon the other. He is also a counterpoint to Galadriel, who needs the temptation and test to know herself and her own desires. Bombadil is also counterpoint to Treebeard the Ent, who takes action against the encroaching evil that Bombadil forgos.
Bombadil, I believe, is Tolkien clearly dividing good from evil and saying flat out, that you can’t, ever, have it both ways: you can’t desire power and yet destroy the ring (indeed — spoiler alert — Frodo can’t do it in the end.) You either don’t desire power and dominion or you do.
Bombadil is, in fact, a very important character in that he counterpoints and highlights a lot of the other characters and underlines Gandalfs’ fear of the ring and/or fear of his own power. Tolkiens genius is to set up these choices again and again without our seeing his machinations.
If you think about it, the only time the hobbits are safe is in the house of Bombadil. Even in Rivendell there is dissension (Bilbo and the Elves regarding his song of Earendil, Boromirs smoldering mistrust) and danger (the tale of Saruman’s treachery and, sadly, Bilbo’s continued, barely contained, desire for the ring) and in Lothlorien it is more so, if you take seriously the notion that Galadriel might well have accepted Frodo’s offer and taken the ring.
Frodo offered Bombadil the ring and Bombadil laughed. Not even Faramir, one of the few characters to freely give up claim to the ring, laughed at the idea. It’s not even clear if Bombadil could destroy the ring: it might not be in his nature to destroy anything; even the barrow wight, when Bombadil rescues the hobbits, is not destroyed by Bombadil but by exposure to the sunlight…
