A big debate is going on at the moment about the future of conservation – much of it centred on the suggestion by Edward Wilson and others that half the world should be allocated to protected areas. Wilson calls this “Half Earth” (HE), and his book of the same name calls for 50% coverage of ‘inviolable natural reserves’. Others have set out various counter-proposals, including “Whole Earth” (WE) and “Sustainable Half Earth” (SHE). I have played a small part in this debate over the last few months, which has given me the chance to observe at close quarters the strange process by which simple and catchy ideas can take hold, even when most people don’t agree with them. In this article I try to tell this curious tale of HE, SHE, WE and me.