Ancient Roman priests were charged with performing the religious rituals with exactness and scrupulous care so as to maintain the gods' good will and support for Rome. They didn't necessarily have to understand the words, but there could be no mistake or untoward event; otherwise, the ceremony would have to be re-staged and the mission delayed. They were administrative officials rather than mediators between men and gods. Over time, the powers and functions changed; some switched from one type of priest to another.
Here you will find an annotated list of the different types of ancient Roman priests prior to the advent of Christianity.
1. Rex Sacrorum
The kings had had a religious function, but when monarchy gave way to the Roman Republic, the religious function could not reasonably be foisted on the two annually-elected consuls. Instead a religious office with life-long tenure was created to handle the king's religious responsibilities. This type of priest even retained the otherwise hated name of king (rex), since he was known as the rex sacrorum. To avoid his assuming too much power, the rex sacrorum could not hold public office or sit in the senate.
The Pontifex Maximus became increasingly important as he took over responsibilities of other ancient Roman priests, becoming -- beyond the time-frame of this list -- the Pope. The Pontifex Maximus was in charge of the other pontifices: the rex sacrorum, the Vestal Virgins and 15 flamines [source: Margaret Imber's Roman Public Religion]. The other priesthoods did not have such a recognized head man. Until the third century B.C., the pontifex maximus was elected by his fellow pontifices.
The Roman king Numa is thought to have created the institution of pontifices, with 5 posts to be filled by patricians. In about 300 B.C., as a result of the lex Ogulnia, 4 additional pontifices were created, who came from the ranks of the plebeians. Under Sulla, the number increased to 15. Under the Empire, the emperor was Pontifex Maximus and decided how many pontifices were necessary.
The augures formed a priestly college separate from that of the pontifices.
While it was the job of the Roman priests to make sure the terms of the contract (so to speak) with the gods were fulfilled, it wasn't self-evident what the gods willed. Knowing the wishes of the gods concerning any enterprise, would enable the Romans to predict whether the enterprise would be successful. The job of the augures was to determine how the gods felt. They accomplished this by divination of omens (omina). Omens might be manifest in bird flight patterns or cries, thunder, lightning, entrails, and more.
The first king of Rome, Romulus, is said to have named one augur from each of the original 3 tribes, the Ramnes, Tities, and Luceres -- all patrician. By 300 B.C., there were 4, and then, 5 more of plebeian rank were added. Sulla appears to have increased the number to 15, and Julius Caesar to 16.
Haruspices also performed divination, but were considered inferior to the augures, although their prestige during the Republic. Of presumed Etruscan origin, the haruspices, unlike the augures and others, did not form a college.
During the reign of one of the Tarquin kings, the Sibyl sold Rome the prophetic books known as the Libri Sibyllini. Tarquin appointed 2 men (duum viri) to tend to, consult, and interpret the books. The duum viri [sacris faciundis] became 10 in around 367 B.C., half plebeian, and half patrician. Their number was raised to 15, perhaps under Sulla.
Source:The Numismatic Circular.
A new college of priests was created in 196 B.C. whose job was to superintend the ceremonial banquets. These new priests were given the honor given to the higher priests of wearing the toga praetexta. Originally, there were triumviri epulones (3 men in charge of the feasts), but their number was increased by Sulla to 7, and by Caesar to 10. Under the emperors, the number varied.
The creation of this college of priests is also credited to Numa. There were probably 20 fetiales who presided over peace ceremonies and declarations of war. At the head of the fetiales was the Pater Patratus who represented the entire body of the Roman people in these matters. The priestly sodalitates, including the fetiales, sodales Titii, fratres arvales, and the salii were less prestigious than the priests of the 4 great priestly colleges -- the pontifices, the augures, the viri sacris faciundis, and the viri epulones.
The flamines were priests attached to the cult of an individual god. They also looked after the temple of that god, like the Vestal Virgins at the temple of Vesta. There were 3 major flamines (from Numa's day and patrician), the Flamen Dialis whose god was Jupiter, the Flamen Martialis whose god was Mars, and the Flamen Quirinalis whose god was Quirinus. There were 12 other flamines who might be plebeian. Originally, the flamines were named by the Comitia Curiata, but later they were picked by the comitia tributa. Their tenure was ordinarily for life. Although there were many ritual prohibitions on the flamines, and they were under the control of the Pontifex Maximus, they could hold political office.
The legendary king Numa is also credited with creating the priestly college of 12 salii, who were patrician men who served as priests of Mars Gradivus. They wore distinctive apparel and carried a sword and spear -- fittingly enough for priests of a war god. From March 1 and for a few successive days, the salii danced around the city, striking their shields (ancilia), and singing.
The legendary king Tullus Hostilius instituted 12 more salii whose sanctuary was not on the Palatine, as was the sanctuary of Numa's group, but on the Quirinal.
The Vestal Virgins lived under the control of the Pontifex Maximus. Their job was to preserve the sacred flame of Rome, sweep out the temple of the hearth goddess Vesta, and to make the special salt cake (mola salsa) for the annual 8-day festival. They also preserved sacred objects. They had to remain virgins and the punishment for a violation of this was extreme.
The Luperci were Roman priests who officiated at the Roman festival of Lupercalia that was held on February 15. The Luperci were divided into 2 colleges, the Fabii and the Quinctilii.
11. Sodales TitiiThe sodales titii are said the have been a college of priests established by Titus Tatius to maintain the rituals of the Sabines or by Romulus to honor the memory of Titus Tatius.
12. Fratres Arvales
The Arvale Brothers formed a very ancient college of 12 priests whose job was to propitiate the gods who made the soil fertile. They were connected in some way with the boundaries of the city.