it started off as a guild or early form of a trade union for skills collaboration and knowledge sharing as many apprentices were required for building castles, forts and chapels. instead of the single master-apprentice relationships that existed in europe then in trades and special skills, groups of men had to be trained due to the massive size of projects. as well regarded tradesmen and masons were being hired and sent across europe they became mobile, trans-kingdom, and free to travel with royal and papal protection. they were very much sought after for their closely guarded skills and knowledge of building immense structures. thus the need to form a cross-boundary union or guild to preserve knowledge, wealth and quiet power accumulated.