The choices that we make (or fail to make) in the coming years about sustainable energy will determine what world future generations will inherit. How do we arrive at rational decisions? In his book, David MacKay does not tell us what to choose but how to. He shows that choosing between different energy options should never be a matter of whom you believe: basic arithmetic is all it takes to distinguish between viable strategies and pipedreams. Understanding our options is one thing. Acting upon this information is another. Therefore, anybody who feels responsible for the future of our society should read this book.