The Priesthoods.

One remarkable feature of Roman religion was that the priests—who were all males except for the Vestal Virgins—were organized into a number of collegia and other small priestly groups, each with a special function to perform. There were four major collegia, a word usually inaccurately translated as "colleges," for they were actually clubs or associations. First there were the fifteen pontiffs, headed by the chief priest or pontifex maximus who was chosen by his colleagues in the early Roman republic. From the third century B.C.E., however, a pontiff would be elected by the Roman people and held office for life. The emperor Augustus became a pontiff early in his career, and as soon as the incumbent pontifex maximus died in 12 B.C.E., he took over the post. The college of pontiffs...