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

The origin of the idiom "the picture of health" is unclear, but it is believed to have originated in the 19th century. It is often used in a complimentary or positive manner to indicate that someone looks healthy, vibrant, and full of energy. This phrase can be employed in various contexts, such as describing someone's appearance, physical condition, or general state of health.