If a being from another planet were to visit Earth, he would find one thing puzzling. He would (as more than one writer has suggested) be able to understand most of the human activity he observed – getting food and shelter, bringing up the young, caring for the unable, settling disputes – activities like these would be clearly and simply related to the needs of an intelligent, gregarious mammal. But there would be other and somewhat inexplicable things. Buildings not used to live or work in, but the scene from time to time of stranger activities – singing, intoning, speech addressed apparently to no one present – and even at other times the place for curiously inhibited behaviour such as speaking in hushed tones or removing shoes. Groves of trees which no one approaches, until one day a group of boys climb them and tear down branches, amid scenes of excitement. A small knot of men giving poison to a fowl and asking it questions as it dies. Or a strange contraption of shells, sticks, feathers, and bits of string, which its owner and others feed with fowl's blood in the belief – contrary to all reason – that it has the power to fly at night and kill an enemy, or set a hut on fire. Such activities would appear quite useless – a waste of time and resources to no benefit.