Tiffany couldn't quite work out how Miss Level got paid. Certainly the basket she carried filled up more than it emptied. They'd walk past a cottage and a woman would come scurrying out with a fresh-baked loaf or a jar of pickles, even though Miss Level hadn't stopped there. But they'd spend an hour somewhere else, stitching up the leg of a farmer who'd been careless with an axe, and get a cup of tea and a stale biscuit. It didn't seem fair.
"Oh, it evens out," said Miss Level, as they walked on through the woods. "You do what you can. People give what they can, when they can. Old Slapwick there, with the leg, he's as mean as a cat, but there'll be a big cut of beef on my doorstep before the week's end, you can bet on it. His wife will see to it. And pretty soon people will be killing their pigs for the winter, and I'll get more brawn, ham, bacon, and sausages turning up than a family could eat in a year."
"You do? What do you do with all that food?"
"Store it," said Miss Level.
"But you--"
"I store it in other people. It's amazing what you can store in other people." Miss Level laughed at Tiffany's expression. "I mean, I take what I don't need round to those who don't have a pig, or who're going through a bad patch, or who don't have anyone to remember them."
"But that means they'll owe you a favour!"
"Right! And so it just keeps on going round. It all works out."
"I bet some people are too mean to pay--"
"Not pay," said Miss Level severely. "A witch never expects payment and never asks for it and just hopes she never needs to. But, sadly, you are right."
"And then what happens?"
"What do you mean?"
"You stop helping them, do you?"
"Oh, no," said Miss Level, genuinely shocked. "You can't not help people just because they're stupid or forgetful or unpleasant. Everyone's poor round here. If I don't help them, who will?"
--Terry Pratchett, A Hat Full of Sky