Wisdom
One of the major themes of this novel is the idea of wisdom; throughout the story, Frodo and his companions rely upon the wisdom and knowledge of their protectors. Gandalf and Tom Bombadil are both examples of figures that are so wise that they seem to embody the very idea of history or time, itself. Wisdom is especially crucial in Frodo's tribulations with the Ring. It takes wisdom for him to reject the temptations to wear the Ring; he also demonstrates his increased wisdom as he learns to hold his tongue. Again and again, wise characters are marked by their ability to wear a "poker face" and hold their tongue.
Sight and surveillance
One thing that we must remember--obvious as it might seem--is the fact that our characters are on the run. Like most heroes, they have a quest and a journey but, unlike most heroes, they are also hiding from their numerous enemies. As a result, this literary work develops the themes of sight and surveillance. We have images like Sauron's evil Eye, the mirror of Galadriel and the Black Riders who are unable to see; we also factor in the repeated instances of attacks and ambushes at night, when the danger cannot be clearly seen. Usually, the ability to see clearly is a metaphor for prudence, morality and steadfastness. In this work, the idea of sight is twisted into so many different images and metaphors. One cannot forget the horror, in the final chapter, when the evil eye of Sauron is awakened and aware of Frodo's spying upon it.
Fate
Fate is a major operator in the trilogy, and never more so than at the very beginning. At the Council of Elrond, it seems clear that only Fate would have brought a timid hobbit through such an obstacle course. The numerous prophecies regarding the ring, its bearer and other travelers like Strider/Aragorn all substantiate the powerful role of Fate. And as is expected, Fate is unpredictable and unknowable. The relationship between fate and will power is especially interesting in Frodo's case because it is only after he is convinced that he is fated for this journey, that he develops the necessary will power and wisdom to survive the challenge.
Individual responsibility
Despite the powerful role of fate and prophecy, Tolkien also defends the role of free will in individual decision-making. This is fully dramatized when Frodo has to make a conscious decision to remove the ring from his finger. Also, we can look at Gandalf's warning at the Council of Elrond, that the ring cannot simply be dumped into the sea, because it will surely be found again. Instead of leaving the ring to Fate, Gandalf argues that they must take responsibility and eliminate the potential danger.