Death used to be a simple affair: either a person’s heart was beating, or it was not. That clarity faded years ago when heroic medical technology started to keep hearts beating in­definitely. Although we have had decades to ponder the distinctions between various states of grave physiological failure, if anything our confusion has grown. When is it ethical to turn off a ventilator or remove a feeding tube? When does “life support” lose its meaning? And most critically, at what point is it acceptable to cut into a body and remove the heart that could save another life?