It's an old magical principle - it's even filtered down into RPG systems - that magic, while taking a lot of effort, can be 'stored' - in a staff, for example. No doubt a wizard spends a little time each day charging up his staff, although you go blind if you do it too much, of course.
Terry PratchettWe're dealing here," said Vimes, "With a twisted mind." "Oh, no! You think so?" "Yes." "But... no... you can't be right. Because Nobby was with us all the time." "Not Nobby," said Vimes testily. "Whatever he might do to a dragon, I doubt if he'd make it explode. There's stranger people in this world than Corporal Nobbs, my lad." Carrot's expression slid into a rictus of intrigued horror. "Gosh," he said.
Terry PratchettThe point is that if a book that had been published three years ago started to sell twice as many all of a sudden it probably wouldn't even get noยญticed. People wouldn't be tracking it. The system has cleaned up its act an awful lot but the best-seller list system is not an entirely foolproof thing.
Terry Pratchett