"It's a sex attraction--not quite the oldest and most primitive thing in the world, but nearly. Only, Darby and Joan aren't primitive people. If they were, the attraction would satisfy itself in a direct primitive way. But each of them is carrying a perfectly enormous superstructure of ideas and inhibitions, emotional refinements and capacities, and the sex attraction is so disguised that they don't recognize it. Do you know what a short circuit is in electricity?" "I think so," said Rose, "but you'd better not take a chance. Tell me that, too." "Why," he said, "the juice that comes into your house to light it and heat the flat-irons and the toaster, and so on, comes in by one wire and goes out by another. Before it can get out, it's got to do all the work you want it to do--push its way through the resistance of fine tungsten filaments in your lamps and the iron wires in your heaters that get white hot resisting it. When it's pushed its way through all of them and done the work you want it to do, it's tired out and goes away by the other wire. But if you cut off the insulation down in the basement, where those two wires are close together, and make it possible for the current to jump straight across without doing any work, it will take the short circuit instead of the long one and you won't have any lights in your house. Now do you see what I mean? "Darby and Joan are civilized. That is to say, they're insulated. The current's there, but it's long-circuited. The only expression it's got is through the intelligence,--so it lights the house. Absence of common knowledge and common interests only adds to the resistance and makes it burn all the brighter. Naturally Darby and Joan fall victims to the very dangerous illusion that they're intellectual companions. They think they're having wonderful talks. All they are doing, is long-circuiting their sex attraction. Well, marriage gives it a short circuit. Why should the current light the lamps when it can strike straight across? There you are!" "And poor Joan," said Rose, after a palpable silence, but evenly enough, "who has thought all along that she was attracting a man by her intelligence and her understanding, and all that, wakes up to find that she's been married for her long eyelashes, and her nice voice--and her pretty ankles. That's a little hard on her, don't you think, if she's been taking herself seriously?"