[Firefoot]

I can think of two passages right now that I feel really applies to this topic.

"Alas! there are some wounds that cannot be wholly cured," said Gandalf.
"I fear it may be so with mine," said Frodo. "There is no going back. Though I may come to the Shire, it will not seem the same; for I shall not be the same. I am wounded with knife, sting, and tooth, and a long burden. Where shall I find rest?

"But," said Sam, and tears started in his eyes, "I thought you were going to enjoy the Shire, too, for years and years, anfter all you have done."
"So I thought too, once. But I have been too deeply hurt, Sam. I tried to save the Shire and it has been saved, but not for me. It must often be so, Sam, when things are in danger: some one has to give them up, lose them, so that others may keep them."

I think that the sacrifice that Frodo made is in and of itself painful beauty. There are other parts of the book that emphasize this but I think that these two sum it up pretty well.