The purpose of this book is to explain how the miracle of pow- erful public speaking is achieved, and to equip you to give it your best shot. But one thing needs emphasizing right at the start. There is no one way to give a great talk. The world of knowl- edge is far too big and the range of speakers and of audiences and of talk settings is far too varied for that. Any attempt to apply a single set formula is likely to backfire. Audiences see through it in an instant and feel manipulated.