"There's no such thing as a single lie."
Via Wizbang's A Tangled Web. It's not just that one lie leads to another; it's that liars tend to lie. It's part of who they are. See People of the Lie, a book about which Amazon quotes:
Scott Peck is a psychiatrist turned author and lecturer. His name is a household word with the self-help crowd. In People of the Lie, Peck takes on the topic of evil. The"volume" cited is not an abridgment but a group of case studies from the first chapters of the book, along with commentary. The presentations are consistently well done. Peck reads with a soft, yet strong voice that is both self-assured and reassuring.