One of my favorite excerpts so far comes from the very beginning before the story even starts. It is profound yet humorous and also rather sad.
A pious man explained to his followers: “It is evil to take lives and noble to save them. Each day I pledge to save a hundred lives. I drop my net in the lake and scoop out a hundred fishes. I place the fishes on the bank, where they flop and twirl. ‘Don’t be scared,’ I tell those fishes. ‘I am saving you from drowning.’ Soon enough, the fishes grow calm and lie still. Yet, sad to say, I am always too late. The fishes expire. And because it is evil to waste anything, I take those dead fishes to market and I sell them for a good price. With the money I receive, I buy more nets so I can save more fishes.”
I love this because it can apply to almost anything. Hitler, the economy, the crusades and pretty much anything else that people are trying to mend or change all come to mind when I read these few sentences. History is riddled with "good intentions" that didn't turn out so good for someone.