Caroline and Alan didn't even glance at each other. They sat there looking at the door through which Humphrey had disappeared, expecting him to return with a crucible or an alembic at the very least. Instead, he came back almost immediately, dangling a piece of very ordinary string.

He smiled at his guests. He gave the string a jerk or two, and in through the door, leaping, frisking, clapping its paws in hot pursuit, came a kitten. Humphrey enticed it right over to where Caroline was sitting, made it jump once or twice. Then he picked it up and handed it to her.

«It's sweet,» said Caroline. «But …»

«It had a birthday last week,» said Humphrey. «Five years old.»

Caroline dropped the kitten as if it were hot. «I hope people will be able to overcome that sort of instinctive prejudice,» said Humphrey, picking it up again and handing it back to her. «Before very long the world will have to get used to this sort of thing.»

«But, Humphrey,» said Caroline, quite agitated, «it's a dwarf or a midget or something.»

«I assure you,» said Humphrey, «that kitten is as normal as any kitten you've ever seen in your life.»

«But what will happen to it? Will it go on forever?» And, as Humphrey shook his head: «Will it go off bang, or crumble into dust or something?»

«Almost surely heart failure,» said Humphrey. «But only after forty years of glorious youth. That's two hundred for a human being. But remember this, both of you …» He paused impressively.

«Yes? Yes?»

«I went to Vienna,» said Humphrey very slowly and clearly, «exactly three years and four months ago. This kitten is five years old. So you see it's Vingleberg's discovery.»

«Oh, yes. Yes, of course. But they said in the papers it was human beings,» said Caroline.

«I was helping Vingleberg adapt it to human beings.»

«And you succeeded?»

«Remember you have promised not to mention this to a living soul. Yes, we succeeded. To a limited extent, that is.»

Alan spoke in a voice at once impatient and businesslike. «Mr. Baxter, you said before very long the world …»

«Humphrey,» said Humphrey with a friendly smile.

«Yes — Humphrey. But … but when?»

«It's a question of finding a new source for the extract,» said Humphrey. «Or possibly making it synthetically, though I doubt we'll ever do that. I should say thirty years. With luck — twenty.»

«Ah!» said Caroline. «I thought you meant now.»

«To get this stuff,» cried Humphrey, «we have to perform an extremely delicate operation, which unfortunately is fatal to the animal we get it from. So it's terribly difficult.»

«What animal?» asked Alan.

«It's quite a common one,» said Humphrey. «Man.»

«Oh!»

«I think we've discovered another source, but it'll take years to test, and more years to manufacture an adequate supply. That's the point. That's why I swore you to secrecy. All merry hell would break loose on this planet if people knew there was just some in existence, being kept for the privileged few.»

«There is some then?» said Caroline.

«The extract has been made,» said Humphrey, «in very odd circumstances, about which I'll tell you exactly nothing — it has been made three times.»

«Three!» exclaimed Alan, as if impressed by the coincidence, because there were three people right there in the room.

«I took one,» said Humphrey with a smile.

«And the others?» cried Caroline.

«Fortunately one dose is enough,» continued Humphrey. «I don't want to bore you with technicalities, but this is extremely interesting. This secretion actually changes the functions of two distinct glands, neither of them the gland from which we originally extracted it. Now …»

«But, Humphrey dear, what happened to the other two doses?»

«Vingleberg took one of them. He's sixty-eight and as ugly as a monkey. He'll stay sixty-eight, and stay ugly, for the next two hundred years.»

«For God's sake!» said Alan bitterly.

«And the third?» asked Caroline.

«Caroline, my dear,» said Humphrey, «I brought that back with me. I needn't tell you why.» As he spoke he unlocked a little drawer in his desk. «Here it is,» he said, holding an ordinary phial full of a colourless liquid. «Life, youth, love, for nearly two hundred years! Probably more, because in that time we'll have found out all sorts of things. I nearly poured this away, the day I landed.»

«Oh, Humphrey, I … what can I say?»

«I don't feel that way any longer,» said Humphrey. «In fact, I didn't from the very first moment I met you both. So I'd like you to have this, if you'd care for it. Call it a sort of belated wedding present. Here you are. To both of you.»

He held out the phial and, finding two hands extended to receive it, he brought them together. «But you do solemnly swear never to say a word?» he asked.

«I do,»said Caroline.

«I do,»said Alan.

«It sounds quite like the wedding service,» said Humphrey with a smile. He laid the phial in their joined hands. «But, of course, it isn't. Well, there it is, for both of you.»

«We shall take half each,» said Caroline.

«A hundred years apiece!» said Alan.

«Here! Wait a minute! Hold on!» said Humphrey. «I'm afraid I've misled you. I suppose one works on a subject for years, and gets so close to it, one forgets other people don't know the first thing. There was an interesting example of that…»

«Why can't we take half each?» said Caroline rather loudly.

«Because, my dear, glands don't understand arithmetic. A half-changed gland won't give you half two hundred years of youth and beauty. Oh, no! Caroline, I remember the very first time I met you I told you what people were like when certain glands were deranged.»

«You mean those awful idiots ?»

«Exactly. This is one dose here, and one dose only. It can be drunk in one gulp; it's got a little flavour, but hardly unpleasant. It's simple, but it's dangerous if you fool with it — like dynamite. Keep it as a curiosity. It's no use; it isn't pretty; it's a wedding present. At least it's unique.»

«Well, thank you, Humphrey. Thank you very, very much.»

Thereupon Caroline and Alan went home, where they set this interesting little bottle on the mantelpiece. They then took a long look at it, and a long look at each other. Had it been possible they might have taken a long look in that enormous mirror, the public eye, before which — almost in which — their lives were lived, and in which they were the perfect lovers.

«You must take it right away,» said Alan. «I'll get you a glass of water to drink afterwards.»

«I shall do no such thing. Alan, I want you to drink it.»

«Darling, come here and look in the glass. Do you see? I'm being perfectly selfish. I want you to be like that forever.»

«I can see you, too, Alan. And that's how you've got to be.»

Some compliments were exchanged. They were sincere and enthusiastic, and became more so. In the end the little bottle was entirely forgotten. But the next morning it was still there.

Alan and Caroline were as determined as ever, each that the other should drink the precious potion. It is impossible to say exactly what it was in their protestations that suggested that each of them may have thought a little about it during the night.

«We can't spend the rest of our lives doing a sort of 'After you, Alphonse,'» said Caroline. «I swear to you; I cross my heart and hope to die — I want you to take it. Now please do.»

«Get this straight once and for all,» said Alan. «You're going to take it, and I'm not. I'm going to be like that fellow what's his name who fell in love with — you know — the goddess.»

«But darling, think of your overhead smash!»

«What's wrong with it? Are you trying to tell me it's not holding up?»