He paused, and glanced down at his equation. It was polished, perfect, like a slab of agate. It had an intrinsic beauty.

The distant glint of the Tower drew his gaze again. He glanced up. Not the right time, not yet. Another hour ...

'And now, Dom, as you stand there torn between shock and astonishment, what do you see? Does your grandmother have that tight-lipped, determined look she wears at times of stress? How was the party, anyway?

'Dom, you are my son, but as you are perhaps learning, I have many sons - untold millions. Have, I say, but "had" I mean. For in those billions of universes that hedge us about on every side, they are dead as I predicted. You, who are flesh and blood, are also that one chance that lies a long trek behind the decimal point. That chance that I am wrong. But a student of probability soon realizes that by its nature the billion-to-one chance crops up nine times out of ten, and that the greatest odds boil down to a double-sided statement: it will happen, or it will not.

'I have studied you, and the billion-to-one universe in which you now stand. It left the main-sequence universe at the point of your non-death. Universes are like the stars which some of them contain. Most follow the well-beaten path. But some, by the twist of a photon, career down strange histories which end in super-novae or impossible holes in space. Rogue universes now, crack under the stress of paradox or - what?

'I will try to give you some help, because you will need it. Your assassin came from your present universe, can you understand that? He wanted to prevent you discovering something that will make your chance-in-a-billion universe the greatest in all the alternate creations. But I've an inkling that whatever saved you from death came from your universe, too. I've seen a lot in your universe but how can I tell you because, believe me, Dom, if I did the paradox burden would split your universe at the seams.'