Pyxeas, cradling the child, seemed to gather what was left of his strength. ‘Indeed. What a tableau we must make – draw us, Nelo! Draw us for history. Myself the elder, who remembers the world before the coming of the longwinter. You adults who are living through this age of transition. And now this little one on my lap, one of a new generation rising already, who knows nothing of the days before the longwinter, and who will grow up thinking all this is normal – to live on a growstone beach, to trap seals to survive. Thus we humans forget the pain of the past. I sometimes think this is the little mothers’ greatest gift, for otherwise each of us, even this little one, would carry inside his head the burden of ten thousand years.

‘But we must not forget. We as a people. Ana, who founded the Wall itself, knew this long ago; we could not forget the great floods of the past, for if we had we would have been doomed to suffer them again. And we did not forget. We wrote down our memories, and organised ourselves, and remembered.

‘Now we face the greatest calamity of all – this longwinter. A flood of cold that will last many thousands of years. Yet we understand why it has come about – I, Pyxeas, a handful of scholars in Carthage, and now these brave boys who brought me home. Knowing why it happens is a long way from being able to turn it back, from warming the world! Only the mothers can do that. But if we understand, if we anticipate, then we can plan. But we can only understand if we remember.

‘I came here hoping to find scholarship surviving. Even I, Pyxeas, I admit, underestimated the damage done by the long-winter in its first few seasons. But what I have found here is you, Crimm, and your people, and your admirable determination to survive. And so I have modified my goals.

‘I have written down my conclusions. I have already sent copies to scholars around the world, from Cathay to Egypt to Carthage. There will be a New Etxelur, built on the Carthaginian shore. That too has copies. But we know the world is in flux, and who knows what will survive of that?

‘But here we are, at the Wall, at Etxelur. And I want you to help me now. I have copies of my findings, stored in my trunk, my conclusions set out. I want more copies made, more sets compiled – more trunks filled. I know you can write, Crimm, you others – you haven’t forgotten yet. And I want these copies distributed in safe places the length of the Wall, as far as you can reach.’