The worship of Vesta, the goddess of the household fire, was one of the most primitive forms of religion.  It doubtless arose from the great difficulty in prehistoric times of producing fire by rubbing two sticks against one another.  Such a flame once procured would be carefully guarded against extinction in some central spot by the unmarried women of the household, who had nothing else to do.  And from this central fire all the household fires of the settlement would be obtained.  A relic of this prehistoric custom existed in the rule that if the sacred vestal fire was ever allowed to go out it could only be kindled anew by the primitive process of friction.  The worship of Vesta survived an old world of exhausted craters and extinct volcanoes, with which was buried a world of lost nations.  The Pelasgians brought to Italy the stone of the domestic hearth, the foundation of the family, and the tombstone, the boundary of the fields divided after the death of the head of the family, the foundation of property; and upon this double base arose the great distinctive edifice of the Roman Law, the special gift of Rome to the civilisation of the world.  Rhea Sylvia, mother of Romulus, was a Vestal Virgin of Alba, which shows that the worship of Vesta existed in this region long before the foundation of Rome.  The origin of the first temple and of the institutions of Vestal Virgins for its service was attributed to Numa Pompilius.  The first building, as Ovid tells us, was constructed with wattled walls and a thatched roof like the primitive huts of the inhabitants.  It was little more than a covered fireplace.  It was the public hearth of the new city, round which were gathered all the private ones.  On it burned continually the sacred fire, the symbol of the life of the state, which was believed to have been brought from Troy, and the continuance of which was connected by superstition with the fortunes of Rome.  In the secret penetralia of the temple, where no man was allowed to enter, was kept with scrupulous care, for its preservation was equally bound up with the safety of the empire, the Palladium, or image of Pallas, saved from the destruction of Troy, and which was supposed to have originally fallen from heaven.  The circular form and the domed roof of the temple were survivals of the prehistoric huts of the Aborigines, which were invariably round, as the traces of their foundations show.  With the exception of the Palladium, which remained invisible during all the ages to ordinary mortal eyes until the destructive fire in the Forum, in the reign of Commodus, compelled the Vestal Virgins to expose it in removing it for safety to the imperial court, there was in primitive times no statue or material representation of the goddess except the sacred fire in the mysterious shrine of the temple.  Indeed the Romans, as Plutarch tells us, raised no statue to the gods until the year of Rome 170.  In this respect the religion of the Romans, whose divinities had no participation in the life and passions of men, and had nothing to do with the human form, differed widely from the religion of the Greeks, which, inspired by the sentiment of the beautiful in man and nature, gave birth to art.