As a quiet hero, Frodo had borne the Ring's baleful imprecations until he stood at the site of its creation. There, in supranormal tones, in a voice unlike his own, he made his lamentable declamation. He would keep the Ring. He submitted to the fearsome, unrelenting temptation of the Ring. He reneged on his oath to the Council. He failed in his quest.
In a letter drafted in September, 1963, to a reader, Mrs Eileen Elgar, who wrote commenting on Frodo's failure, Tolkien explained that the hobbit's failure to resist the might of the Dark Lord came at the end of a heroic struggle. The Professor also expressed his belief that Frodo's failure to endure to the end was not a moral failure.
"At the last possible moment the pressure of the Ring would reach its maximum - impossible, I should have said for any one to resist, certainly after long possession, months of increasing torment, and when starved and exhausted. Frodo had done what he could and spent himself completely... and had produced a situation in which the object of his quest was achieved." ('The Letters of JRR Tolkien', H. Carpenter editor, letter #246)
Thus, by Tolkien's moral standard and by the Northern tradition of defeated heroes such as Beowulf, his hero is exculpated and forgiven for his transgression, his weakness. Frodo is, after all, presented as an every-man who chose to assume a heroic role as his duty to his fellows. As a mortal being, he had done all he could. Tolkien asserted that "the breaking of Frodo's mind and will under demonic pressure after torment was any more a moral failure than the breaking of his body would have been..."(ibid letter #246)
