All my life, I have been fascinated by the big questions that face us, and have tried to find scientific answers to them.

Unsourced variant: All of my life, I have been fascinated by the big questions that face us, and have tried to find scientific answers to them. Perhaps that is why I have sold more books on physics than Madonna has on sex. This quote seems to combine the above sentence from Stephen Hawking's Universe with a statement from the Foreword to The Illustrated Brief History of Time: As Nathan Myhrvold of Microsoft (a former post-doc of mine) remarked: I have sold more books on physics than Madonna has on sex.