Science of Discworld III

Auditors, being embodiments of physical laws, find it hard to deal with nonsensical or contradictory instructions. Therefore, I have prepared these.’
    He flourished something that looked like a table-tennis bat. On it were printed the words: ‘Do Not Read This Sign.’
    ‘That works, does it?’ said the Dean, doubtfully.
    ‘It’s said to put their minds into a fugue state, Dean. They feel confused and alone, and evaporate instantly. Being alone means having a sense of self, and any Auditor that develops an individuality is said to die instantly.’
    ‘And the catapult bows?’ What are they for?’ said the Archchancellor, slapping the Dean’s hand off one of them.
    ‘In addition, it is possible that a collective of Auditors with sufficient presence in the material world may develop crude physical senses, and so I have adapted some catapult bows to fire a mixture of intense, er, stimuli. Old references suggest chilli, essence of Wahoonie or Blissberry blossoms, but modern thinking inclines to Higgs & Meakins Luxury Assortment.’
    ‘Chocolate?’ said Ridcully.
    ‘They don’t like it, sir.’
    ‘But those things can live in empty space and inside stars, man!’
    ‘Where chocolate is significantly absent, sir,’ said Ponder, patiently. ‘They keep away from it. Also, it comes handily packed. They particularly don’t like the Strawberry Whirl.’
    Ridcully picked up a bow, pointed it at a wizard, and fired. There was a distant ‘ow!’
    ‘Hmm. Spreads nicely on impact,’ he said. ‘Well done, Mr Stibbons. I’m impressed. You are in charge.’
    The Dean bridled at this. ‘I protest! I am the Dean, when all is said and done!’
    ‘Oh, all right , Dean, you can come! But, and I want to make myself absolutely clear, you are not to point anything at anything unless I give you a clear instruction, understood?’
    ‘Yes, Mustrum,’ said the Dean meekly.
    ‘Furthermore, you will not, at any point, wave your weapon in the air and shout “choc and load”. Is that clear? I say that because I can practically see the silly words forming in your head!’
    ‘That’s a vile calumny!’ the Dean shouted.
    ‘I hope so. Stibbons, wait here with the proctors and see no harm comes to Mr Darwin. Hex, you know where to send us. Invisibly, if you please!’
    While Charles Darwin was sitting in a blue haze in Unseen University, a slightly younger Charles Darwin was staring out at the rain, noting idly that the rain sounded a little like whispering.
    A drawback of invisibility is that no one can see you; it is in fact the main drawback if there is a group of you –
    ‘– that was my foot! ’
    ‘ Who is that? ’
    ‘ Look where you ’re going! ’
    ‘ And what help will that be? ’
    ‘ Keep it down, you fellows! He’ll hear you! ’
    At which point, the wall in the corner dissolved and brilliant light shone through. Beetles of all sizes and colours poured into the study in a shimmering torrent.
    A figure that the wizards recognised stepped though the hole and looked around him with an air of amiable bewilderment. He had a slightly lopsided circlet of leaves on his head, and glowed with the light of deity.
    ‘Mr Darwin?’ he said, as the figure in the corner turned and stared. ‘I understand you are studying evolution and are currently perplexed?’
    ‘Look behind him!’ Ridcully whispered.
    The unseen wizards stared into the flickering hole. There was sand, and sea in the distance, a suggestion of moving shadows …
    ‘After me,’ Ridcully hissed, as an astonished Darwin dropped to his knees. ‘Let’s get them …’
    The wizards poured through the camiloop, while behind them an elderly voice said: ‘Of course, selection is, ahaha, anything but natural. Take, for example, a species of parasitic wasp …’
    The sand boiled. Sometimes handfuls of it fountained into the air. One invisible person can move with stealth and speed. Half a dozen invisible people are an accident waiting to happen again and again.
    ‘This is not being our finest hour,’ said the voice of Ridcully. ‘Every time I start to stand up someone else treads on me! Can’t Hex sort this out?’
    ‘We’re back in the real world,’ said the invisible Dean. ‘Hex’s power isn’t so strong here. It’ll take him some time to find us. Would you mind getting off my leg. Thank you so very much.’
    ‘That’s not me, I’m over here. I don’t see why it’s a problem. We were in another world, after all!’
    ‘Roundworld