Sun and Moon allegory
The Sun and Moon allegory is used to depict a medieval political theory of hierocracy which submits the secular power to the spiritual power, stating that the Bishop of Rome is like the Sun, the only source of his own light, while the Emperor is like the Moon, which merely reflects lights and has no value without the Sun. It was espoused by the Catholic Church of Innocent III and instantiated to some extent in medieval political practice. It was among the first ambitions of papal domination of Europe.
Description
Finding this imagery in the Book of Genesis, the Allegory images authentic spiritual authority as the Sun and any and all civil, or political or secular, authority as the Moon. By doing so, it illustrates that the Roman Catholic Pope, as "Supreme Pontiff", "Vicar of Christ", et cetera, and therefore the supreme universal spiritual authority on Earth, is like the Sun that is the one source of light for itself and all other celestial bodies orbiting it; while the Holy Roman Emperor, as symbolic and intended supreme civil, political, and secular authority on Earth, and having theoretically received his authority from and at the pleasure of the Pope, is like the Moon – that is, dependent upon the Sun for any illumination, merely reflects solar light, and ultimately has no light without the Sun. This theory dominated European political theory and practice in the 13th century. It is related to the general theory of Papal supremacy and "plenitudo potestatis" as articulated by the Roman Catholic Church.In 1215, this concept was reflected in Canon 3 of the Fourth Lateran Council regarding heretics:
While this theory of papal sovereignty in temporal as well as spiritual matters was, by the fourteenth century, generally rejected as out-of-date, it entered into canon law and was reinforced by the Allegory of the Two Swords in the bull of Pope Boniface VIII entitled Unam Sanctam. Dante Alighieri argued contrarily to the Allegory of the Sun and Moon in his De Monarchia. In this work, he explicitly rejects the allegory of the sun and the moon, and defends that the Emperor is the supreme authority on secular matters, while the Pope is the supreme authority in spiritual matters, none of them having precedence or supremacy over the other. For some time, the work was placed on the Index due to this heterodox conception of Catholic politics.