We talk about artistic license today and joke that it is a license to practice art, never realising that in fifteenth century Florence it was necessary for an artist to literally pass a test to become a licensed practitioner. If he and his skills were sufficiently mature to satisfy the examiners, he was admitted to the Guild of St. Luke, which was primarily a sort of labour union for doctors. Just why artist and doctors should belong to the same guild seems to be a mystery other than the fact it was probably the most prestigious of all the guilds and the artists decided they needed all the prestige they could get. At any rate, the guilds demanded of their members only the highest standards of competence and workmanship. Beyond that, they also guaranteed the work of their members. Believe it or not, they also celebrated religious rituals and as the name implies, each had a patron saint. These guilds controlled all branches of labour from butchers to plumbers and all the skills in between. Today, the Masonic Order is a throwback to such medieval guilds.
About the age of twelve, boys and their families made a decision as to the trade he would follow. In most cases it was an irrevocable decision. The boy would then be apprenticed to a master craftsman, be it a painter, a sculptor, jeweller, or whatever. The daily life of a junior painting apprentice was not pleasant. He learned such skills as sweeping out the studio, taking out the garbage, feeding the dog, and cleaning the toilet, the fireplace, and the front steps. And every day he drew, for at least an hour a day he drew, usually from a live model, and from the back of the room, lucky to merit even a passing glance from the master. Day by day he honed his skills, hoping that one day he might become an assistant to the master. Only after several years of menial tasks did the young apprentice begin learning tasks and techniques peculiar to his chosen trade. Such chores might include finding and grinding pigments, making and cleaning brushes, mixing plaster, punching holes in cartoons used in fresco, and transferring them to wet plaster. It the painting master worked in oils, the apprentice might find himself preparing panels or stretching and sizing canvases.
In becoming a senior apprentice, the talented would-be artist found himself working intimately with the master and actually getting paid for his efforts (what we would today call "slave wages"). In many studios, the senior apprentices and assistants (sort of senior, senior apprentices) actually worked on the various commissions obtained by the studio with the master artist primarily concerned with the initial conception and beginning composition. Under the watchful eye of the master, assistants would then complete most of the painting except for faces and perhaps areas involving the human anatomy. The master did these and also completed minor finishing touches or corrections before signing the work and claiming all the credit for himself. This educational system developed as early as Roman times and continued well into the eighteenth century when the various national art academies grew to prominence in European cities. The guilds actually continued even long after that.