Jupiter, also referred to as Jove, was the Roman equivalent of Zeus.
When the early Romans adopted Greek mythology, there were few changes made to Zeus’s general character or position. A few stories and functions were added to tie him into Italian history, but the god himself remained relatively unchanged.
While the mythology surrounding the king of the gods remained almost identical, his role in daily life did not. Jupiter took on a prominent role in the state religion of the growing Roman world, first as the patron of the Republic and later as a symbol of Imperial authority.
The differences in political and social structure meant that Jupiter was far more important to the citizens of Rome that Zeus had been to most residents of Greece.
As Latin culture arose in Italy, it was influenced by its neighbors. It borrowed many gods and their names from the nearby Etruscans and other Italian tribes but, as far as historians have been able to gather, lacked any narrative mythology.
This changed when the early Romans came into contact with the people of Greece. The Greeks who lived in Italian colonies and traded locally introduced the people of the early Roman kingdom to their pantheon and its complex mythology.
The Romans soon adopted the stories of Greece as their own. Many gods retained their Latin names but their stories and relationships were taken almost wholly from the legends told by the Greeks.
Zeus, the sky god and king of the Olympians in Greece, became the Roman Jupiter.
Like many aspects of the god’s mythology, even his name underwent only minor changes when he was brought to Rome. Jupiter comes from the phrase djous pater, or sky father, with the proto-Indo-European djous also being the root for Zeus.
Jupiter was also called Jove, the genitive form of this root.
In most ways, Jupiter was almost identical to his Greece predecessor. He was the king of the pantheon and the ruler of the sky, with the same family relationships and specific stories that had been known in Greece.
One difference in how the myths were presented was that the Romans put much less emphasis on the birth and childhood of their sky god than the Greeks had. This is, perhaps, because this particular legend was more difficult to place within Roman territory.
As was often the case, the Romans eventually added new tales to more closely tie the god to their own land. One story, for example, told of how the impious King Tullus was struck down by one of Jupiter’s lightning bolts for failing to heed the god’s commands.
A few additional domains and powers were ascribed to Jupiter that had not been associated with Zeus. He was considered to be highly important in winemaking, for example, because grapes were particularly susceptible to harsh weather.
Most myths, however, remained relatively unchanged and the role the god played in the pantheon was very nearly identical. In the state religion, however, the role of Jupiter was more complicated than Zeus’s had been.
As a divine king, his power was similar to that of the Emperor’s in later Roman history. Under the Empire the leaders promoted Jupiter as a parallel to their own right to unchallenged and complete rule.
While emperors modelled themselves after the king of the gods, there was already a long precedent of Jupiter being the patron of the Roman state as a whole. This made him a god of all the people, which could lead to conflict as well as unity.
Roman society was strictly divided between the patricians, the nobility, and the plebians, the common people. Each claimed that Jupiter gave them special political rights.
The patricians believed that their status was a sign of Jupiter’s favor and, like the king of the gods, they had a divine right to their privilege. The plebians, on the other hand, claimed that Jupiter was the arbiter of justice and was thus sympathetic to the righteousness of their demands for greater political power.
The belief held by both sides that they had the favor of Jupiter meant that neither was willing to back down in particularly heated political battles. The Roman Republic nearly fell into civil war on two occasions over the political disputes between the classes.
These incidents highlighted the most significant way in which the Roman Jupiter differed from the Greek Zeus.
While Zeus had been a definitively noble god, the social and political structure of Rome made him a symbol for all the people of the state. The poor soldiers who marched under the sign of the eagle, Jupiter’s sacred bird, believed that he supported their rights as much as the leaders of the Senate believed that they had his favor.
Once Rome took control of its neighbouring states in the pre-Republican era, it had a distinctly different political and social structure than Greece ever did. Rather than being a collection of independent cities bound only by a shared language and religion, the Romans began establishing a unified state.
This meant that less emphasis was placed on local patron gods and regional legends. The state religion of Rome was more unified and centralized, with feasts and rites operating on a shared calendar.
There were more feast days devoted to Jupiter on the Roman calendar than to any other god. As the king of the pantheon, he was the de facto primary god of the state religion.
This had not been the case in Greece, where the people of each city-state had held their own local patron in the highest esteem. Zeus had been the king of the pantheon, but that had not translated to great devotion on Earth.
This was also because Zeus had been associated only with the nobility. Under Rome, Jupiter was the god of all the citizens of the state, a position that became more important as the Republic was formed.
As the creator of law, Jupiter was the source of the Senate’s authority and their inspiration. Unlike Greece, power over Jupiter’s laws was in the hands of the people.
Even during the brief period of Athenian democracy, political power had been concentrated in the hands of a few wealthy men. In the Republic, however, the lower classes gained more of an immediate connection to law-making.
In reality, most tribunes of the plebs were far wealthier than their constituents and most power remained concentrated in the hands of the nobility. Even then, however, the power of Jupiter was more relevant and accessible than it had been under the reigns of kings in either Rome or Greece.
When the people of Rome adopted the stories of the Greek gods, Zeus was renamed Jupiter. The names share a common root word and are one way in which the transition was relatively subtle.
Jupiter held the same position in his pantheon as Zeus had, retained the family relationships detailed in Greek myths, and had a similar temperament and personality. Only minor changes were made, mostly in a common practice of creating stories to link the gods with Italy in addition to Greece.
In practice, however, the worship of Jupiter was very different.
The Roman pantheon was not centered around local practices and city patrons, but around the state religion. As Rome expanded its control through Italy and beyond, Jupiter became the official chief god of a widespread pantheon.
This meant that while Zeus had been secondary to more local gods in many parts of Greece, Jupiter was more universally recognized as the most powerful god.
As a state god, his importance was also not as limited by class as that of Zeus. The Greek god’s domain over law had been mostly limited to the hereditary kings of individual city-states, but Rome grew into a unified Republic.
This meant that more people had a direct tie to Jupiter’s authority than had ever been possible under the Greek system. Even the lower classes had an opportunity to elect tribunes who would represent them in making and interpreting laws.
This sometimes lead to class conflict, as both the upper and lower classes believed that they had the favor of Jupiter, but it also united people under a common political system.
In later years, emperors would use Jupiter as a template for their own divine authority. By then, however, Jupiter’s role had already expanded to be a patron of all the people who lived under the rule of Rome.