Old Belgian banknote, depictingCeres, Neptune and caduceus.

Comparative mythology is the systematic comparison of myths from different cultures.^[2] It seeks to discover underlying themes that are common to the myths of multiple cultures.^[2] In some cases, comparative mythologists use the similarities between different mythologies to argue that those mythologies have a common source. This common source may be a common source of inspiration (e.g. a certain natural phenomenon that inspired similar myths in different cultures) or a common "protomythology" that diverged into the various mythologies we see today.^[2]

Nineteenth-century interpretations of myth were often highly comparative, seeking a common origin for all myths.^[53] However, modern-day scholars tend to be more suspicious of comparative approaches, avoiding overly general or universal statements about mythology.^[54] One exception to this modern trend is Joseph Campbell's bookThe Hero With a Thousand Faces (1949), which claims that all hero myths follow the same underlying pattern. This theory of a "monomyth" is out of favor with the mainstream study of mythology.^[54]