One of things I love about Nietzsche is his ability to pack a whole essay or maybe even a book into a single sentence. One of my favorites is about how our sincere attachment to bad or false ideas can do more damage than deliberate falsehoods. Think Bush building up to Iraq invasion, European war plans in 1914, tinkle down economics, utopias induced by violence, etc. etc. etc.
Here's the passage:
Convictions are more dangerous enemies of truth than lies.