The dark side of the sun - By Terry Pratchett Page 0,15

dome near the administrative centre of Tau City. Even Lady Vian came out to meet him, bundled in a heavy cloak, and looking slightly happier for being in a city. Tau was not overwhelmingly cosmospolitan, though a sight more so than the home domes.

‘That is not a becoming colour,’ were her first words.

They dined in the small hall. Down the table Samhedi and the senior members of the household eavesdropped respectfully. Joan, after a polite enquiry about the hospital, was silent.

Vian looked across at her son. ‘Why don’t you try those body cosmetics?’

Dom caught the eye of a security man standing against the wall. He had one green hand and a green patch extended all down one cheek and into the colour of his uniform. The man saw him and winked.

‘I prefer it this way.’

‘Perverse vanity,’ said Joan. ‘But still, I agree. A piebald grandson I could not bear, but at least he is a uniform colour.’

She pushed her plate aside and added: ‘Besides, green is a holy—’

‘Green is the colour of chlorophyll on Earth, certainly,’ said Vian, ‘but here the vegetation is blue.’

Joan glanced up quickly at the Sadhim logo inscribed on the ceiling and then gazed at her daughter-in-law, her eyes narrowing. Dom watched them interestedly – too much so, for Joan sensed him and folded her napkin deliberately. She stood up.

‘It is time,’ she said, ‘for our evening devotions. Dom, I will see you in my office in one hour’s time. And we will talk.’

4

Dom entered. His grandmother glanced up, and nodded towards a chair. The air was musty with incense.

The large white-painted room was completely empty except for the small desk and two chairs and the little standard thurible and altar in one corner, though Joan had a way of filling up empty spaces with her presence.

In foot-high letters along the facing wall the ubiquitous One Commandment glared down on them.

Joan closed her account book and began to play with a white-hilted knife.

‘In a few days it’ll be Soul Cake Friday, and also the Eve of Small Gods,’ she said. ‘Have you given much thought to joining a klatch?’

‘Not much,’ said Dom, who hadn’t thought at all about his religious future.

‘Scares you, eh?’

‘Since you put it like that, yes,’ said Dom. ‘It’s a rather final choice. Sometimes I’m not sure Sadhimism has all the answers, you see.’

‘You’re right, of course. But it does ask the right questions.’ She paused for an instant, as if listening to a voice that Dom could not hear.

‘Is it necessary?’ prompted Dom.

‘The klatch? No. But a bit of ritual never did anyone any harm, and of course it is expected of you.’

‘There is one thing I’d like to get clear,’ said Dom.

‘Go ahead.’

‘Grandmother, why are you so nervous?’

She laid down the knife and sighed.

‘There are times, Dom, when you raise in me the overwhelming desire to bust you one on the snoot. Of course I’m nervous. What do you expect?’ She sat back. ‘Well, shall I explain, or will you ask questions?’

‘I’d like to know the story. I think I’ve got some kind of right. A lot has been happening to me lately, and I kind of get the impression that everyone knows all about it except me.’

Joan stood up, and walked over to the altar. She hoisted herself onto it and sat swinging her legs in an oddly girlish way.

‘Your father – my son – was one of the two best probability mathematicians the galaxy has ever seen. You have found out about probability math, I gather. It’s been around for about five hundred years. John refined it. He postulated the Pothole Effect, and when that was proved, p-math went from a toy to a tool. We could take a minute section of the continuum – a human being, for example – and predict its future in this universe.

‘John did this for you. You were the first person ever quantified in this way. It took him seven months, and how we wish we knew how he managed it, because even the Bank can’t quantify a person in less than a year with any degree of accuracy. Your father had genius, at least when it came to p-math. He … wasn’t quite so good at human relationships, though.’

She shot an interrogative glance at Dom, but he did not rise to the bait. She went on: ‘He was killed in the marshes, you know.’

‘I know.’

John Sabalos looked out over the sparkling marshes, towards the distant tower. It was a fine day. He