What is the origin of the idiom "for dear life" and when to use it?

The origin of the idiom "for dear life" can be traced back to the early 19th century. The word "dear" in this context is used in its older sense of "precious" or "highly valued." The phrase likely emerged as a metaphorical expression to describe the intense effort and urgency with which one clings to or holds on to something in order to protect their own life or well-being. The term "dear life" carries the connotation of something cherished and worth preserving at all costs. It is commonly employed in discussions or descriptions of physical danger, such as gripping onto a ledge or railing during a fall, desperately swimming in turbulent waters, or tightly clutching onto a safety line during a dangerous activity.