Pignora imperii

The pignora imperii ("pledges of rule") were objects that were supposed to guarantee the continued imperium of Ancient Rome. One late source lists seven. The sacred tokens most commonly regarded as such were the Palladium, the wooden image of Minerva (Greek Athena) that the Romans claimed had been rescued from the fall of Troy and was in the keeping of the Vestals; the sacred fire of Vesta tended by the Vestals, which was never allowed to go out; and the ancilia, the twelve shields of Mars wielded by his priests the Salii in their processions, dating to the time of Numa Pompilius, second king of Rome.

In the later Roman Empire, the maintenance of the Altar of Victory in the Curia took on a similar symbolic value for those such as Symmachus who were trying to preserve Rome's religious traditions in the face of Christian hegemony. The extinguishing of the fire of Vesta by the Christian emperor Theodosius I is one of the events that mark the abolition of Rome's ancestral religion and the imposition of Christianity as a state religion that excluded all others.

In late antiquity, some narratives of the founding of Constantinople claim that Constantine I, the first emperor to convert to Christianity, transferred the pignora imperii to the new capital. Though the historicity of this transferral may be in doubt, the claim indicates the symbolic value of the tokens.

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