What is the origin of the idiom "a brick wall" and when to use it?

The origin of the idiom "a brick wall" can be traced back to the early 20th century. It comes from the analogy of running into or hitting one's head against an actual brick wall, which is immovable and impenetrable. In modern usage, it can refer to any situation where a person or group is facing a significant obstacle or challenge that seems insurmountable.