Creating this book is a team sport. Like so many human achievements, it reflects
a collective intelligence. Woodrow Wilson spoke for us: “I not only use all the brains I
have, but all I can borrow.” The thousands of instructors and millions of students across
the globe who have taught or studied with this book have contributed immensely to its
development. Much of this contribution has occurred spontaneously, through correspondence
and conversations. And we look forward to continuing feedback as we strive,
over future editions, to create an ever better book and teaching package.