The Elegant Universe (paperback version) is easily the most accessible book on modern (and postmodern?) physics I have ever encountered. The examples, metaphors, and analogies Brian Greene uses to explain the concepts of general relativity and quantum mechanics, both of which are extremely complicated and difficult to understand (even for physicists), can be understood by anyone with a bit of curiosity and determination. Even when he attempts to explain superstring theory, which combines and greatly magnifies the complexity of relativity and quantum mechanics, he lays everything out for the reader, explaining, restating, and then restating again in plain English the most difficult concepts in physics. Highly recommended.