To: CHARLES FABIUS GRANVER,
Sector 233, Zone 3, Home 1254, Radli.
The Thirty-Fourth Century, a.d.
My dear great-great-great-etc.-grandson Charles:
Your friend Hari Vans will discover this letter printed as a fiction story in an ancient, tattered book of still more ancient fiction stories in the rare-books stacks of the University Library. He will be astonished to see your name and still more astonished to read his own. He will be astounded to find your correct address in a volume printed when neither you nor your address existed. So he will show this letter to you, and in this way I can write you a very important message. The ordinary postal service could hardly be expected to deliver a letter after fourteen centuries, and I feel I must tell you about urgent family matters.
I need to arrange, through you, to meet and woo (and of course to win, despite your unfilial objections) your great-great-etc.-grandmother. When this letter is delivered, she will happen to be engaged to you, so I do not really count on your co-operation. The most I expect is a frantic effort on your part to prove that the whole business is pure lunacy. But that effort will be all I need, Charles, and I think that for the family’s sake you should make it. It really is a family matter. As nearly as I can compute it on a basis of four generations to the century, you are my great-great-etc.-grandson some fifty-two times removed. This relationship exists because of a somewhat unusual series of events, and you need to know what to do to bring them about.
To make it clear… I imagine that in your day they still talk of time-travel as impossible because, so the argument runs, if one went back in time a hundred years, landed on his grandfather, and happened to kill him, he would make it impossible for himself to have been born. But of course if he wasn’t born his grandfather wouldn’t be killed. So he would be born. So he would kill his grandfather. So he wouldn’t be born. Ad infinitum. I am sure you know this proof that time-travel is impossible.
However, I am your great-great-etc.-grandfather because of just the reverse of this classical paradox. It happens that when you read this, you are about to discover me as a visitor come forward from my time to yours. And in your time, with your extremely reluctant assistance, I shall woo and win your current girl friend and bring her contentedly back to my century to become your fifty-two-times-removed-grandmother.
I hardly expect you to approve the notion, Charles. You are inclined to be selfish. You will resist my great-grandparental authority, not caring about the consequences to the family. But I think you will flub it. After all, if you did manage to keep me from wooing and winning Ginny, you would not be born to stop me. So I would woo and win her, in which case you would be born to stop me. If you did such a thing, you would not be born. In short, I think I am going to marry Ginny. In fact, I already have, and now I want to arrange for it.
Let me clarify the situation a little. In my senior year at Collins University, my physics professor was Prof. Knut Hadley, Ph.D., M.A. etc., etc. He was a person with a sort of monorail mind, capable of following an idea tenaciously over dizzy heights of improbability and through fastnesses of opposing facts. In the previous semester he’d tracked an idea down. It was a dilly. As class-work, he had five of us seniors help him put together an incredibly complicated electronic gadget that he said would provide experimental proof of the verity of the Lorenz-Fitzgerald equation. His theory was—