Consider Phlebas

command centres of a state which once existed on the planet, when it was at the intermediate-sophisticated stage-three phase. State-of-the-art weaponry at the time was the fusion bomb, delivered by transplanetary guided rocket. The Command System was designed to-'

'Yes.' Fal waved her hand quickly. 'Protect, keep mobile so they couldn't be blown up. Right?'

'Yes.'

'What sort of rock cover did they have?'

'Granite,' Jase said.

'Batholithic?'

'Just a second,' Jase said, consulting elsewhere. 'Yes. Correct: a batholith.'

'A batholith?' Fal said, eyebrows raised. 'Just one?'

'Just one.'

'This is a slightly low-G world? Thick crust?'

'Both.'

'Uh-huh. So the Mind's inside these…' She looked along the terrace, not really seeing anything, but in her mind's eye looking down kilometres of dark tunnels (and thinking there might be some pretty impressive mountains above them: all that granite; low-G; good climbing territory). She looked at the machine again. 'So what happened? It's a Planet of the Dead; did the natives eventually do it to themselves?'

'With biological weapons, not nukes, to the last humanoid, eleven thousand years ago.'

'Hmm.' Fal nodded. Now it was obvious why the Dra'Azon had made Schar's World one of their Planets of the Dead. If you were a pure-energy superspecies long retired from the normal, matter-based life of the galaxy, and your conceit was to cordon off and preserve the odd planet or two you thought might serve as a fitting monument to death and futility, Schar's World with its short and sordid history sounded like the sort of place you'd put pretty near the top of your list.

Something occurred to her. 'How come the tunnels haven't sealed up again over all that time? Five klicks' worth of pressure…'

'We don't know,' Jase sighed. 'The Dra'Azon have not been very forthcoming with information. It is possible the System's engineers devised a technique for withstanding the pressure over such a period. This is unlikely, admittedly, but then they were ingenious.'

'Pity they didn't devote a little more ingenuity to staying alive rather than conducting mass slaughter as efficiently as possible,' Fal said, and made a little snorting noise. Jase felt pleasure at the girl's words (if not the snort), but at the same time detected in them a tinge of that mixture of contempt and patronising smugness the Culture found it so difficult not to exhibit when surveying the mistakes of less advanced societies, even though the source civilisations of its own mongrel past had been no less fallible. Still, the underlying point held; experience as well as common sense indicated that the most reliable method of avoiding self-extinction was not to equip oneself with the means to accomplish it in the first place.

'So,' Fal said, looking down as she tapped her one good heel on the grey stones, 'the Mind's in the tunnels; the Dra'Azon's on the outside. What's the Quiet Barrier limit?'

'The usual half-distance to the nearest other star: three hundred and ten standard light-days in the case of Schar's World at the moment.'

'— And…?' She held out her hand to Jase and raised her head and her eyebrows. Flower shadows moved on her neck as the gentlest of breezes started and ruffled the blossoms on the trelliswork above her head. 'What's the problem?'

'Well,' Jase said, 'the reason the Mind was allowed in at all was because-'

'In distress. Right. Go on.'

Jase, who had stopped being annoyed by Fal's interruptions the first time she had brought it a mountain flower, went on, 'There is a small base on Schar's World, as there is on almost all the Planets of the Dead. As usual it is staffed from a small, nominally neutral, non-dynamic society of some galactic maturity-'

'The Changer,' Fal broke in, quite slowly, as though guessing the answer to a puzzle which had been troubling her for hours and ought to have been simple. She looked through the flower-strewn trellis, to a blue sky where a few small white clouds were moving slowly. She looked back to the machine. 'I'm right, aren't I? That Changer guy who… and that Special Circumstancer — Balveda — and the place where you have to be senile to rule. They're Changers on Schar's World and this bloke-' She broke off and frowned. 'But I thought he was dead.'

'Now we're not so sure. The last message from the GCU Nervous Energy seemed to indicate he might have escaped.'

'What happened to the GCU?'

'We don't know. Contact was lost while it was trying to capture rather than destroy the Idiran ship. Both are presumed lost.'

'Capture it, eh?' Fal said tartly. 'Another show-off Mind. But that's it, isn't it? The Idirans might be able to use this guy — what's his name? Do we know?'

'Bora Horza Gobuchul.'

'Whereas we don't have any Changers.'

'We do, but the one we have is on the other side of the galaxy on an urgent job not connected with the war; it would take half a year to get her there. Besides, she has never been to Schar's World; the tricky part about this problem is that Bora Horza Gobuchul has.'

'Ho-ho,' Fal said.

'In addition, we have unconfirmed information that the same Idiran fleet which knocked out the fleeing ship also tried unsuccessfully to follow the Mind to Schar's World with a small landing force. Thus the Dra'Azon concerned is going to be suspicious. It might let Bora Horza Gobuchul through, as he has served before with the caretaker staff on the planet, but even he is not certain to gain entry. Anybody else is very doubtful indeed.'

'Of course the poor devil might be dead.'

'Changers are not notoriously easy to kill, and besides, it would seem unwise simply to count on that possibility.'

'And you're worried he might get to this precious Mind and bring it back to the Idirans.'

'It could just happen.'

'Just supposing it did happen, Jase,' Fal said, screwing up her eyes and leaning forward to look at the machine, 'so what? Would it really make any difference? What would happen if the Idirans did get their hands on this admittedly resourceful kid Mind?'

'Assuming that we are going to win the war…' Jase said thoughtfully, '… it could lengthen the proceedings by a handful of months.'

'And how many's that supposed to be?' Fal said.

'Somewhere between three and seven, I suppose. It depends whose hand you're using.'

Fal smiled. 'And the problem is that the Mind can't destruct without making this Planet of the Dead even more dead than it is already, in fact without making it an asteroid belt.'

'Exactly.'

'So maybe the little devil shouldn't have bothered saving itself from the wreck in the first place, and should have just gone down with the ship.'

'It's called the instinct to survive.' Jase paused while Fal nodded, then it went on, 'It's programmed into most living things.' It made a show of weighing the girl's injured leg in its field-held grip. 'Though, of course, there are always exceptions…'

'Yes,' Fal said, giving what she hoped was a condescending smile, 'very droll, Jase.'

'So you see the problem.'

'I see the problem,' Fal agreed. 'Of course we could force our way in there, and blow the place to smithereens if necessary, and to hell with the Dra'Azon.' She grinned.

'Yes,' Jase conceded, 'and put the whole outcome of the war in jeopardy by antagonising a power whose haziest unknown quantity is the exact extent of its immensity. We could also surrender to the Idirans, but I doubt we'll do that either.'

'Well, so long as we're considering all the options.' Fal laughed.

'Oh yes.'

'OK, Jase, if that's all — let me think about this lot for a while,' Fal 'Ngeestra said, sitting up straight on the