I sliced the heart in two with a big kitchen knife. All was revealed--the four chambers separated by moist, gristly valves that suck blood into auricles and squeeze it out ventricles. Eleven years old and fascinated, I asked my mother if, next time, she could bring me a brain. When she returned from the butcher shop with a calf brain, I beamed and cleaved the melon in two. But inside I saw nothing notable. Just a hollow cavity at the core of a fleshy mush.