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

The phrase "the man" is used to refer to an individual who possesses a high degree of skill or experience in a particular activity or profession. The phrase is believed to have originated in the 19th century, when it was used to refer to a man who was considered to be the best at his job. The phrase has since become more widespread, and it is now used to refer to any person who is considered to be an expert in their field.