The beginning of the industrial and scientific revolutions of the 1800s, however, turned brewing irrevocably from an intuitive craft into a process based on sophisticated scientific and engineering knowledge. The entire system was regulated by closed-shop tradesmen guilds that issued certificates and controlled both entry into and advancement within the profession. As secular brewing arose in the high Middle Ages, brewers’ training became regularized in the form of a three-tier tradesman’s training process, in which an aspiring brewer started at the bottom as an apprentice, then took to the road as an itinerant journeyman, finally to settle down as a master brewer. In the early Middle Ages, brewing knowledge resided mostly among the learned friars in the monasteries, who, being literate, were able to write down recipes, perfect their techniques, and pass on their knowledge over time. Before that time, brewers essentially learned their craft by doing it and were often taught by family members. People have brewed for at least 8,000 years, but brewing schools, perhaps surprisingly, are a phenomenon of only the past 150 years. They provide formal practical and theoretical training in those branches of science and engineering that are relevant for beer making on a commercial scale in a modern brewery. Brewing Schools, institutions of higher learning that offer programs designed specifically for aspiring brewing professionals.