Sometimes, figures of speech can also produce a texture or theme at the same time they perform a function and carry a meaning.
Winston Churchill, repeatedly used archetypal (universal) metaphors of "light" to characterize the British military and citizenry and "dark" ones for the enemy.
Archetypal metaphors usually refer to common substances or events like light and dark, birth/death, and rite of passage, and frequently are associated with the sacred or profane.