“...what about this rule about not meddling?’ said Magrat.
‘Ah,’ said Nanny. She took the girl’s arm. ‘The thing is,’ she explained, ‘as you progress in the Craft, you’ll learn there is another rule. Esme’s obeyed it all her life.’
‘And what’s that?’
‘When you break rules, break ‘em good and hard…”
―
Terry Pratchett,
Wyrd Sisters