"Well, maybe I'd better explain. I'm coming to see you're sincere in claiming ignorance. Not that I can accept that silly story about the twentieth century. But judging from your looks, your queer accent and out-of-date manners, you are undoubtedly from some foreign country, where maybe the people are uncivilized and don't know anything about decapitation." The black-robed one seated himself on a little revolving stool, crossed his legs, and slowly went on: "The original invention was made about three hundred years ago, by a physician named John Knight, who lived in an ancient city called New York. Was it necessary, Knight asked, for our best and most brilliant minds to be taken from us at the early age of seventy or eighty owing to some bodily defect? If fed by a vigorous blood-stream, the brain would continue to function indefinitely--perhaps for centuries. But a vigorous blood-stream, after senility had set in, could come only from another body. Therefore, Dr. Knight concluded, if an old man's head were grafted on to the body of a youth, the old man might continue to live, with new limbs and organs, but with mental faculties unimpaired. Think what a boon it would be for the race, if we could keep our great geniuses alive for hundreds of years!" "But how was it possible, Doctor," broke in Downey, "to attach one man's body to another man's head?" "It wasn't possible until after long experimentation. But the same principle had already been applied in the grafting of limbs. There was a gas, Etherene by name, which would produce suspended animation for a few hours, even stopping the heartbeat and the circulation of the blood. Any part of a man's body might be cut off while he was in this condition; and if ligament was fitted to ligament, bone to bone, and blood-vessel to blood-vessel, the removed portion might be attached in its proper place to the body of another Etherene patient. Of course, this required skilled surgery. But it was found that, by making proper measurements in advance, it was possible to graft arms, legs, ears, eyes and even whole bodies on to new possessors." "That doesn't explain," remarked Downey, grimly, "where the new bodies would come from."