The Revolution

During the first chapters of the book people rarely spoke badly of Trujillo because his spies might've been listening. So I was wondering...if the government has such a close watch on the citizens, how come they haven't noticed the underground revolution? I mean, I know the people involved use code words, but still, you'd think the government would notice that something is going on. Maybe Trujillo actually did know it was happening, but Julia Alvarez hasn't written about it yet.