What is the origin of the idiom "keep a level head" and when to use it?

The origin of the idiom "keep a level head" can be traced back to nautical terminology. In sailing, a "level head" referred to the situation where a ship's compass remained level and steady despite the vessel's movement on the water. It symbolized stability, balance, and an accurate sense of direction. It is often invoked during times of stress, conflict, or uncertainty, such as in high-pressure work environments, intense negotiations, or personal crises.