Fun little thing about medieval medicine.
So there's this old German remedy for getting rid of boils. A mix of eggshells, egg whites, and sulfur rubbed into the boil while reciting the incantation and saying five Paternosters. And according to my prof's friend (a doctor), it's all very sensible. The eggshells abrade the skin so the sulfur can sink in and fry the boil. The egg white forms a flexible protective barrier. The incantation and prayers are important because you need to rub it in for a certain amount of time.
It's easy to take the magic words as superstition, but they're important.
The length of time it takes to say a paternoster was a typical method of reckoning time in the Middle Ages. It's likely that whoever wrote this remedy down was thinking of it both as a prayer and a timespan and that whoever read it would have understood it the same way.
It's sort of like the time version of people today saying 'this dinosaur was two school buses long'.