“Everything really began at that party of Rupert’s. (He doesn’t know about this, by the way, though he put me on the right track.) You remember that silly seance he arranged and how it ended when that girl — I forget her name — fainted? I’d asked what star the Overlords came from, and the reply was ’NGS 549672. I’d not expected any answer, and had treated the whole business as a joke until then. But when I realized that this was a number in a star catalogue, I decided to look into it. I found that the star was in the constellation Carina— and one of the few facts that we do know about the Overlords is that they come from that direction.
“Now I don’t pretend to understand how that information reached us, or where it originated. Did someone read Rashaverak’s mind? Even if they had, it’s hardly likely that he would have known the reference number of his sun in one of our catalogues. It’s a complete mystery, and I leave it to people like Rupert to solve — if they can! I’m just content to take the information, and to act on it.
“We know a lot now, through our observation of their departure, about the speed of the Overlord ships. They leave the Solar System under such tremendous accelerations that they approach the velocity of light in less than an hour. That means that the Overlords must possess some kind of propulsive system that acts equally on every atom of their ships, so that anything aboard won’t be crushed instantly. I wonder why they employ such colossal accelerations, when they’ve got all space to play with and could take their time picking up speed? My theory is that they can somehow tap the energy fields round the stars, and so have to do their starting and stopping while they’re fairly close to a sun. But that’s all by the way….
“The important fact was that I knew how far they had to travel, and therefore how long the journey took. NGS 549672 is forty light-years from Earth. The Overlords ships reach more than ninety-nine per cent of the speed of light, so the trip must last forty years of our time. Our time: that’s the crux of the matter.
“Now as you may have beard, strange things happen as one approaches the speed of light. Time itself begins to flow at a different rate — to pass more slowly, so that what would be months on Earth would be no more than days on the ships of the Overlords. The effect is quite fundamental: it was discovered by the great Einstein more than a hundred years ago.
“I have made calculations based on what we know about the stardrive, and using the firmly-established results of Relativity theory. From the viewpoint of the passengers on one of the Overlord ships, the journey to NGS 549672 will last not more than two months — even though by Earth’s reckoning forty years will have passed. I know this seems a paradox, and if it’s any consolation it’s puzzled the world’s best brains ever since Einstein announced it.
“Perhaps this example will show you the sort of thing that can happen, and will give you a clearer picture of the situation. If the Overlords send me straight back to Earth, I shall arrive home having aged only four months. But on Earth itself; eighty years will have passed. So you understand, Maia, that whatever happens, this is goodbye.
“I have few ties binding me here, as you know well enough, so I can leave with a clear conscience. I’ve not told mother yet: she would get hysterical, and I couldn’t face that. It’s better this way. Though I’ve tried to make allowances, ever since father died — oh, there’s no point now in going into all that again!
“I’ve terminated my studies and told the authorities that, for family reasons, I’m moving to Europe. Everything has been settled and there should be nothing for you to worry about.
“By this time, you may imagine that I’m crazy, since it seems impossible for anyone to get into one of the Overlord ships. But I’ve found a way. It doesn’t happen very often, and after this it may never happen again, for I’m sure Karellen never makes the same mistake twice. Do you know the legend of the Wooden Horse, that got the Greek soldiers into Troy? But there’s a story from the Old Testament that’s an even closer parallel… ”