Now if you have been abroad for five years, it is a great deal to know that you have any intimate friend at all still left in the metropolis, and, as Louis said, to have that intimate friend next door, is an excellent reason for going next door. Above all, I remembered from Cambridge days, what Louis’ ‘dropping in’ meant. Towards bed-time, when work was over, there would come a rapid step on the landing, and for an hour, or two hours, he would gush with ideas. He simply diffused life, which is ideas, wherever he went. He fed one’s brain, which is the one thing which matters. Most people who are ill, are ill because their brain is starving, and the body rebels, and gets lumbago or cancer. That is the chief doctrine of my work such as it has been. All bodily disease springs from the brain. It is merely the brain that has to be fed and rested and exercised properly to make the body absolutely healthy, and immune from all disease. But when the brain is affected, it is as useful to pour medicines down the sink, as make your patient swallow them, unless--and this is a paramount limitation--unless he believes in them. I said something of the kind to Louis one night, when, at the end of a busy day, I had dined with him. We were sitting over coffee in the hall, or so it is called, where he takes his meals. Outside, his house is just like mine, and ten thousand other small houses in London, but on entering, instead of finding a narrow passage with a door on one side, leading into the dining-room, which again communicates with a small back room called ‘the study,’ he has had the sense to eliminate all unnecessary walls, and consequently the whole ground floor of his house is one room, with stairs leading up to the first floor. Study, dining-room and passage have been knocked into one; you enter a big room from the front door. The only drawback is that the postman makes loud noises close to you, as you dine, and just as I made these commonplace observations to him about the effect of the brain on the body and the senses, there came a loud rap, somewhere close to me, that was startling. ‘You ought to muffle your knocker,’ I said, ‘anyhow during the time of meals.’ Louis leaned back and laughed. ‘There isn’t a knocker,’ he said. ‘You were startled a week ago, and said the same thing. So I took the knocker off. The letters slide in now. But you heard a knock, did you?’ ‘Didn’t you?’ said I. ‘Why, certainly. But it wasn’t the postman. It was the Thing. I don’t know what it is. That makes it so interesting.’