Here is the blackness of space, the myriad stars gleaming like diamond dust or, as some people would say, like great balls of exploding hydrogen a very long way off. But then, some people would say anything. A shadow starts to blot out the distant glitter, and it is blacker than space itself.

From here it also looks a great deal bigger, because space is not really big, it is simply somewhere to be big in. Planets are big, but planets are meant to be big and there is nothing clever about being the right size.

But this shape blotting out the sky like the footfall of God isn't a planet. It is a turtle, ten thousand miles long from its crater-pocked head to its armoured tail.

And Great A'Tuin is huge.

Great flippers rise and fall ponderously, warping space into strange shapes. The Discworld slides across the sky like a royal barge. But even Great A'Tuin is struggling now as it leaves the free depths of space and must fight the tormenting pressures of the solar shallows. Magic is weaker here, on the littoral of light. Many more days of his and the Discworld will be stripped away by the pressures of reality.

Great A'Tuin knows this, but Great A'Tuin can recall doing all this before, many thousands of years ago.

The astrochelonian's eyes, glowing red in the light of the dwarf star, are not focussed on it but at a little patch of space nearby . . .

© Terry Pratchett