It’s sometimes said that a great novel makes a less promising basis for a film than a novel which is merely good.  I don’t think that adapting great novels presents any special problems which are not involved in adapting good novels or mediocre novels; except that you will be more heavily criticized if the film is bad, and you may be even if it’s good.  I think almost any novel can be successfully adapted, provided it is not one whose aesthetic integrity is lost along with its length.  For example, the kind of novel in which a great deal and variety of action is absolutely essential to the story, so that it loses much of it’s point when you subtract heavily from the number of events or their development.

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You might wonder, as a result of this, whether directing was anything more or less than a continuation of the writing.  I think that is precisely what directing should be.  It would follow, then, that a writer-director is really the perfect dramatic instrument; and the few examples we have where these two peculiar techniques have been properly mastered by one man have, I believer, produced the most consistently fine work.

Go read the whole damn thing, please.