As soon as any man says of the affairs of the State "What does it matter to me?" the State may be given up for lost.
Any good movie is filled with secrets. If a director doesn't leave anything unsaid, it's a lousy picture. If a picture's unsaid, it's a lousy picture. If a picture is good, it's mysterious, with things unsaid.
It is the task of the scenarist to invent little pieces of business that are so characteristic and give so deep an insight into his creatures, that their personalities clearly and organically unfold before the eyes of the audience so that the latter feel that the actions of these people are contingent upon their characters, that there exists some kind of a logical fate, and that nothing is left to mere accident or coincidence.