What is the origin of the idiom "past master" and when to use it?

The idiom "past master" originated in the context of various trade guilds and fraternities during the Middle Ages and the Renaissance. In these organizations, individuals progressed through a series of stages or degrees of skill and knowledge. When a person had achieved the highest degree or level of mastery, they were known as a "past master." This phrase recognized their experience, knowledge, and expertise within the guild or fraternity. This expression is used to describe someone who is highly skilled, experienced, or knowledgeable in a particular field or activity. It indicates a person who has achieved a level of expertise that goes beyond being merely competent; they are considered a true master in their domain.