Before the eleventh century, most painters in Europe were monks (members of a religious group that lives in seclusion) and their work was exclusively religious. Such artists worked in a variety of art forms, including metalwork and manuscript illumination (the art of illustrating handwritten books), and they did not sign their work, as art was considered an opportunity for religious meditation, not self-advancement. Between the eleventh and the fourteenth centuries, however, painting began being practiced by lay professionals, who had no connection to religious institutions. Inevitably, this had consequences both for working practices and for the art that was produced. These new painters followed a trade like any other. Like the woodworker, the potter, the baker, and the weaver, the lay painter offered his technical proficiency for a fee. He was by no means above asking the baker for use of his ovens to make charcoal, employed as a black pigment. Nor would the artist sneer at the cook with whom he had many skills in common.

One of the consequences of this transition from monk to artisan was increasing specialization. Painters were painters, not to be confused with illuminators, dyers, or workers in wood and metal. Such distinctions were rigidly enforced by the guilds-powerful associations of workers within specific trades-that developed to safeguard the employment of tradespeople against competition and economic uncertainty, so that it would have been unthinkable for a painter to be called in to illuminate a book page. There were even fine distinctions drawn among painters. In fifteenth-century Spain one could find specialists in altarpiece painting (the painting of images for placement behind the altar of a church), fabric painting and interior decorating. Associated with these divisions was a hierarchy of trades in which status tended to reflect the value of the materials. Goldsmiths were the most prestigious and powerful artisans. painters more humble, and woodworkers still more so. Guild restrictions prohibited the use of the most valuable pigments (coloring substances), such as ultramarine, for lowly purposes such as the painting of playing cards, carts, or parrot perches. Thus these valuable pigments played a role in establishing the social standing of painters: it was in their interests to use fine materials.

Yet the art of painting was still regarded as a mechanical process. There was good and bad, to be sure, but the task of the painter was to meet the specifications of a contract, not to give free expression to artistic inspiration. It was the employer-the patron-who made the decisions. Initially, the patrons of lay painters, when not church-affiliated, tended to be royal or aristocratic, and the painter could find himself affiliated to a court. But as a prosperous middle class emerged during the fourteenth and later centuries, the base of patronage broadened, and artists could find commissions (orders for artworks) among merchants.

Membership in a guild was attained by apprenticeship. Aspiring painters would serve a training period of typically between four and eight years in a workshop operated by a master craftsman, beginning as all apprentices do with the most menial of jobs, such as grinding pigments and making glue. Pigment grinding was a particularly arduous and time-consuming job, and painters might need to allow several days for this alone in their scheduling for a commission. To qualify as a "master painter" ready to accept contracts, an apprentice would present a "master piece" to the guild for approval. Strange, then, that this term has come to refer to an artist's most accomplished piece of work rather than his or her first attempt to gain recognition.

A workshop undertook a commission as a group, much as a band of builders would (and still does) perform a job collectively. The master was responsible for the overall execution of the work, but the application of paint to surface was as much, if not more, the responsibility of his apprentices. Thus the signatures that appear on fourteenth- and fifteenth-century art are simply trade stamps, denoting the name of the workshop's master. This traditional training placed little value on personal talent or inspiration: a person became a painter simply through hard work, dedication, and adherence to the master's demands. Skill was the product of diligence.