Metaphors are one of the most extensively used literary devices. A metaphor refers to a meaning or identity ascribed to one subject by way of another. In a metaphor, one subject is implied to be another so as to draw a comparison between their similarities and shared traits.
The first subject, which is the focus of the sentences is usually compared to the second subject, which is used to convey a degree of meaning that is used to characterize the first. The purpose of using a metaphor is to take an identity or concept that we understand clearly (second subject) and use it to better understand the lesser known element (the first subject).
“Henry was a lion on the battlefield”. This sentence suggests that Henry fought so valiantly and bravely that he embodied all the personality traits we attribute to the ferocious animal. This sentence implies immediately that Henry was courageous and fearless, much like the King of the Jungle.