What is the origin of the idiom "run its course " and when to use it?

The idiom "run its course" has its origins in the field of medicine and dates back to the 16th century. It is derived from the idea of a disease or illness following a natural progression and ultimately resolving itself without intervention. The term "course" refers to the path or trajectory that an illness or condition takes until it reaches its expected outcome. It is often used when discussing the resolution of illnesses or diseases, indicating that the body's natural healing mechanisms will take effect and the condition will improve over time.