What is the origin of the idiom "set in one's ways" and when to use it?

The origin of the idiom "set in one's ways" can be traced back to the early 19th century. The term "set" in this context refers to becoming fixed or firmly established in a particular pattern or behavior. The phrase likely evolved from the idea of setting or hardening materials, such as clay or cement, which become rigid and unyielding once they have solidified. It is often employed when discussing someone's behavior, attitudes, or preferences that have become fixed and unyielding over time.