During the Middle Ages, a family worked in a trade for generations, with fathers training sons and passing knowledge along bloodlines. Masons learned how to carve elaborate gargoyles; glaziers made intricate stained-glass windows. These skilled workers were organized into guilds, and on a construction site, guild workers were highly esteemed while lower-level unskilled workers completed simple routine tasks. All laborers were paid. His specialty did not fall under masonry or glazing.
He had signed a contract forgoing payment in exchange for on-the-job training.
He was not born into a family of skilled laborers.
He did not pass the necessary exams to qualify for guild membership.