Knowledge
Knowledge remains just as important in The Two Towers as in the first part of the trilogy. When Gandalf returns as Gandalf the White, he is even more powerful than he was before and most of this power comes from his increased knowledge and wisdom. We also find that Saruman and Sauron may be defeated by their lack of knowledge. They do not know precisely where the Ring is, and they know too little about the forces of good to realize that Gandalf and his associates may seek to destroy the Ring rather than use it for their own gain. Most of the knowledge of the quest comes from the legends and songs; characters are at an advantage if they know the prophecies. Though what we find quite often is that those who know the songs and legends, are nonetheless surprised when they learn that the characters and creatures mentioned in the songs do, in fact, exist.
Heroism and Honor vs. Cowardice and Deception
Like most works of this genre, The Two Towers has plenty of heroes and there are customs and values that are a part of heroism. Book Three begins with fallen Boromir, who is not heroic in trying to take advantage of Frodo, who is weaker, hoping to steal the Ring from him. Boromir's brother, Faramir, is a contrast to Boromir for when he has an opportunity to claim the Ring for himself, Faramir remembers his promise and instead, offers assistance to the hobbits (in place of treachery). For their part, the members of the Fellowship (Aragorn and Frodo, most notably) are honorable in their concealing of Boromir's crime. The burial at sea is also a noble act. The evil characters are cowardly traitors. One of the logistical concerns of Evil, is the inability to keep the individuals from growing rebellious. In characters like Gollum/Sméagol, Saruman, and Grishnákh, we see that the forces of evil shoot themselves in the foot because so many of these individuals desire the Ring for themselves and they would happily rebel against their leader.
Fate
Fate is perhaps the most important theme of the work. From the very first chapter (Boromir's departure) through the final chapter (regarding Sam's choices), fate is generally on the side of good and it seems that good will inevitably win out over evil. Repeatedly, unintended actions and mistakes turn out to produce benefits that could not have been imagined. In the first part of the trilogy there was a struggle between free will and fate in terms of a hero's destiny. In The Two Towers, the individual fates of the heroes are not as important at the fate of the Ring. We see how fate might be described as fickle and quickly changing. Gandalf, for example, seemed to be dead, but then he arose victorious, as Gandalf the White. Similarly, Frodo seems dead at the end of Book 4, but as fate would have it, the hobbit turned out to be merely drugged.
