Warning: this may perhaps contain spoilers.
I’m a fairly big fan of Goodkind’s Sword of Truth series, which just concluded with the release of the book “Confessor”. Although at first glance fantasy, the series is actually more of a Objectivist philosophical treatise (at least towards the end) than a collection of fantasy novels. Each book states its theme rather clearly in the form of a “wizard’s rule”, which can sort of be viewed as the “take-home lesson” from the book.
Anyway, the last book threw us all for a loop because the wizard’s rule, and thus the theme, is not given to us. It’s introduced as the “secret of a war wizard’s power”, but the book by that name in the series is discovered to be blank.
After some thought, I’ve come to the conclusion that this is not only intentional, but that this IS the rule. It’s also how Richard (the protagonist) ultimately triumphs at the end of the book – the antagonists did not understand the rule, but he did, which is why even their moment of triumph was ultimately defeat.
I believe it is this:
Truth is sought internally. Truth handed down is insufficient; truth reasoned out is not. You must come to your own conclusions.
Not only does it fit the nature of the rule itself (nothing written down), but it is also a recurring theme in the book: why the antagonists could not accomplish their objective despite having precise instructions to do so (they didn’t think, they just obeyed) and why Richard and Kahlan’s love could endure (because it was twice discovered independently rather than simply told).