Merism refers to the whole by mentioning its opposing or representative parts, as in “night and day,” “young and old,” or “body and soul.” A poet who says that sorrow followed someone “through dawn and dusk” means that it endured continually. The device can make totality feel concrete by breaking it into vivid poles. It is common in sacred, ceremonial, and lyric language because paired extremes create both rhythmic balance and a sense of comprehensiveness.

Merism names opposite ends, parts, or divisions to suggest the entirety between them. “Night and day,” “young and old,” and “from shore to shore” imply completeness rather than only two separate things. The device is common in biblical, ceremonial, and lyrical language because it makes a total idea concrete. It is related to synecdoche, though merism specifically works through paired extremes.