What are some themes of Rick Riordan's book The Last Olympian?

Rick Riordan’s book The Last Olympian
deals with a number of significant themes, including the
following:

• Courage:
  Courage is required by many characters in the novel, especially the young
  hero Percy Jackson.  Thus, at one point Paul says to Sally (Percy’s mother),
  

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. . . it sounds to me . . . it sounds like Percy
is doing something noble. I wish I had that much
courage.

• Physical
  bravery, as when Zeus commends Tyson for his bravery in
  war.


• Evil, a trait
  frequently illustrated by
  Kronos.


• Luck, since many
  characters frequently wish each other good
  luck.


• Death, a theme
  mentioned constantly throughout the
  book.


• War, a major focus of
  much of the novel, which consists of one battle after another. At one memorable point,
  for instance, when Percy’s mother asks what he will do next, her son
  replies,

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“I go to war. . . . Me against Kronos. And only
one of us will
survive.”

• Virtue
  versus Vice, as in the quotation just cited, in which Percy represents
  virtue and Kronos represents vice.

All the
themes just mentioned are highly appropriate to a novel that describe the battle to save
all that is good and just from all that is evil and vicious.