Why Frodo Could Not Destroy the Ring: Tolkien's Own Explanation

Frodo never actually manages to destroy the ring, and Tolkien was very clear about why. He actually starts showing it right near the beginning of the story, long before Frodo ever reaches Mount Doom.

Frodo already fails to destroy the ring once, at home in the Shire

Early on, Gandalf basically tells Frodo to go on then, try and do it, get on with it. Frodo goes to throw the ring into his own fireplace, but then he can't. That moment matters because of where Frodo is when it happens. He's at home, nobody's stabbed him, nobody's poisoned him.

At Mount Doom, Frodo refuses outright: "The ring is mine"

Jump forward to The Return of the King, and Frodo has now carried the ring for months. He's standing inside the one place where the ring can actually be destroyed. And then he says, "I will not do this deed, the ring is mine."

Tolkien's letters explain the pressure finally broke Frodo's will

Tolkien later explained what was happening here, and it's in his letters. He says that at the final moment the pressure of the ring basically reached its maximum, and that after everything Frodo had endured, resistance had effectively become impossible. He even describes Frodo's mind and will as finally breaking under that pressure.

So yes, Frodo failed to destroy the ring, but Tolkien did not consider Frodo a moral failure for it. He simply reached the limit of what he was capable of enduring.

Gollum, spared earlier, ends up finishing what Frodo could not

Frodo spared Gollum earlier in the story. Because Gollum was still alive, he followed Frodo into Mount Doom and took the ring, then fell into the fire with it. That's why Frodo later tells Sam, "But for him, Sam, I could not have destroyed the ring."

Frodo carried the ring as far as his strength could take him, and when that strength finally ran out, the mercy he'd shown earlier just finished the job. That's about as Tolkien as Tolkien gets.

Do you think Frodo's failure at Mount Doom should count against him, or does Tolkien's explanation settle it for you?