What is the meaning of Herman Melville's novella Billy Budd? What is the moral of the novella?

Although it is common (and correct) to say that few
literary works have a single “meaning,” this claim is especially appropriate when the
subject is Herman Melville’s novella Billy Budd. In fact,
Melville’s novella is written in a way that makes diverse, even contradictory,
interpretations almost maddeningly easy to reach. Often, the effect of reading the book
or even individual chapters or paragraphs is similar to suffering from vertigo.
Sometimes it seems less that we are reading Billy Budd than that
Billy Budd is reading us. Interpretations of
the book tend to reflect, even more than is the case with most works of art, the values
and perspectives we bring with us to our reading.

The
central point of dispute in many readings of Billy Budd involves
the justice of Billy’s execution and the moral character of Captain Vere. Some readers
find Vere a sympathetic and even tragic figure who finds himself in an extraordinarily
difficult ethical position.  Other readers consider Vere a cold, calculating figure who
engineers a guilty verdict when none is necessary.  Some other readers regard Vere as a
character who may be literally insane in his treatment of
Billy.

After Vere tells the ship’s surgeon that he intends
to put Billy on trial for killing Claggart, he surgeon immediately (but privately)
wonders if Vere may be acting irrationally. He considers the decision “impolitic,” if
nothing else.  The surgeon thinks the trial should be postponed until the
Bellipotent can rejoin its squadron, so that the matter can be
turned over to the admiral. Yet although the surgeon communicates his ideas to other
officers, and although they share his ideas, the trial proceeds. Billy is found guilty
and is hanged.

Are we meant to sympathize with the
surgeon’s doubts about Vere? Are the surgeon’s thoughts about how to handle the case
ones with which we should agree? Can the surgeon fully appreciate the complexity of the
situation, especially considering that the
Bellipotent is indeed separated from
its squadron, that the military situation is extremely tense, and that mutinies have
recently occurred in the British fleet? Does Vere make a compelling case when he
addresses the court? Later in the book, after all, the narrator, quoting an unidentified
author, writes,

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Says a writer whom few know, “Forty years after
a battle it is easy for a noncombatant to reason about how it ought to have been fought.
It is another thing personally and under fire to have to direct the fighting while
involved in the obscuring smoke of it. Much so with respect to other emergencies
involving considerations both practical and moral, and when it is imperative promptly to
act. . . . (end of Chapter
21)

Who is this writer?
Should we take his opinions seriously? Are the quoted opinions in fact relevant to
Vere’s case? Does this passage imply the narrator’s agreement with the writer he quotes?
Does the rest of the paragraph – which compares a commander in battle to the captain of
a befogged ship, which must move quickly even at the risk of running someone down – work
in Vere’s favor, or does it raise even more doubts about Vere’s
conduct?

Critics have famously debated the “moral” of
Billy Budd for many decades (especially since the 1960s), and one
of the reasons the novella is so compelling is that it raises serious moral issues in a
context that makes clear moral judgments, at least for some readers, difficult to
adopt.