“Well, now,” she said, because she'd learned a lot in the last twenty years or so, “that's as may be, and I'll always do the best I can, ask anyone. But I wouldn't say I'm the best. Always learnin' something new, that's me.”

“Oh. In that case I will call at a more convenient… moment.”

“Why've you got snow on—?”

But, without ever quite vanishing, the stranger was no longer present…

Tick

There was a hammering on the door. Nanny Ogg carefully put down her brandy nightcap and stared at the wall for a moment. Now a lifetime of edge witchery

On the hob the kettle for her hot-water bottle was just coming to the boil.

She laid down her pipe, got up and opened the door on this springtime midnight.

“You've come a long way, I'm thinking,” she said, showing no surprise at the dark figure.

“That is true, Mrs Ogg.”

“Everyone who knows me calls me Nanny.”

She looked down at the melting snow dripping off the cloak. It hadn't snowed up here for a month.

“And it's urgent, I expect?” she said, as memory unrolled.

“Indeed.”

“And now you got to say, ‘You must come at once.’”

“You must come at once.”

“Well, now,” she said. “I'd say, yes, I'm a pretty good midwife, though I do say it myself. I've seen hundreds into the world. Even trolls, which is no errand for the inexperienced. I know birthing backwards and forwards and damn near sideways at times. Always been ready to learn something new, though.” She looked down modestly. “I wouldn't say I'm the best,” she said, “but I can't think of anyone better, I have to say.”

“You must leave with me now.”

“Oh, I must, must I?” said Nanny Ogg.

“Yes!”

An edge witch thinks fast, because edges can shift so quickly. And she learns to tell when a mythology is unfolding, and when the best you can do is put yourself in its path and run to keep up.