Free Lords and Ladies by Terry Pratchett

referencing system, actually ,” said Diamanda.
    “Ah.”
    A gust rocked the cottage. The door burst open and slammed back against the wall, giving a glimpse of cloud-wracked sky in which a nonmimetic convention was showing a crescent.
    Diamanda waved a hand. There was a brief flash ofoctarine light. The door jerked shut. Diamanda smiled in what Perdita thought of as her cool, knowing way.
    She placed the card on the black velvet cloth in front of her.
    Perdita looked at it gloomily. It was all very pretty, the cards were colored like little pasteboard jewels, and they had interesting names. But that little traitor voice whispered: how the hell can they know what the future holds? Cardboard isn’t very bright.
    On the other hand, the coven was helping people…more or less. Raising power and all that sort of thing. Oh dear, supposing she asks me ?
    Perdita realized that she was feeling worried. Something was wrong. It had just gone wrong. She didn’t know what it was, but it had gone wrong now. She looked up.
    “Blessings be upon this house,” said Granny Weatherwax.
    In much the same tone of voice have people said, “Eat hot lead, Kincaid,” and, “I expect you’re wondering after all that excitement whether I’ve got any balloons and lampshades left.”
    Diamanda’s mouth dropped open.
    “’Ere, you’re doing that wrong. You don’t want to muck about with a hand like that,” said Nanny Ogg helpfully, looking over her shoulder. “You’ve got a Double Onion there.”
    “Who are you ?”
    Suddenly they were there. Perdita thought: one minute there’s shadows, the next minute they were there , solid as anything.
    “What’s all the chalk on the floor, then?” said NannyOgg. “You’ve got all chalk on the floor. And heathen writing. Not that I’ve got anything against heathens,” she added. She appeared to think about it. “I’m practic’ly one,” she added further, “but I don’t write on the floor. What’d you want to write all on the floor for?” She nudged Perdita. “You’ll never get the chalk out,” she said, “it gets right into the grain.”
    “Um, it’s a magic circle,” said Perdita. “Um, hello, Mrs. Ogg. Um. It’s to keep bad influences away…”
    Granny Weatherwax leaned forward slightly.
    “Tell me, my dear,” she said to Diamanda, “do you think it’s working?”
    She leaned forward further.
    Diamanda leaned backward.
    And then slowly leaned forward again.
    They ended up nose to nose.
    “Who’s this?” said Diamanda, out of the corner of her mouth.
    “Um, it’s Granny Weatherwax,” said Perdita. “Um. She’s a witch, um…”
    “What level?” said Diamanda.
    Nanny Ogg looked around for something to hide behind. Granny Weatherwax’s eyebrow twitched.
    “Levels, eh?” she said. “Well, I suppose I’m level one.”
    “Just starting?” said Diamanda.
    “Oh dear. Tell you what,” said Nanny Ogg quietly to Perdita, “if we was to turn the table over, we could probably hide behind it, no problem.”
    But to herself she was thinking: Esme can never resist a challenge. None of us can. You ain’t a witch if you ain’t got self-confidence. But we’re not getting anyyounger. It’s like being a hired swordfighter, being a top witch. You think you’re good, but you know there’s got to be someone younger, practicing every day, polishing up their craft, and one day you’re walkin’ down the road and you hears this voice behind you sayin’: go for your toad, or similar.
    Even for Esme. Sooner or later, she’ll come up against someone faster on the craftiness than she is.
    “Oh, yes,” said Granny, quietly. “Just starting. Every day, just starting.”
    Nanny Ogg thought: but it won’t be today.
    “You stupid old woman,” said Diamanda, “you don’t frighten me. Oh, yes. I know all about the way you old ones frighten superstitious peasants, actually . Muttering and squinting. It’s all in the mind. Simple psychology. It’s not real