Knowledge on adjunct fields and skills can accumulate in a person over time, thus allowing them to perform similar feets.
Like, a bright pupil might learn from a master, if it is not intended. It has happend- since medieval times- apprenticeships, although a attack on caste-think can happen today. Yes, they did not jump through the money hoops, that are suppossed to keep them away- but some of them studied what happens around them. Those servant peoples.. they might not be automatons.