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—

No. I spare you that, Charles. Let’s keep this simple. You just remember that if you manage to keep me from winning Ginny you won’t be born to keep me from winning Ginny, so I will win her and you will be born to try and stop me—you see? Just bear that in mind if you get confused. It may help.