Fear has been the original parent of superstition, and every new calamity urges trembling mortals to deprecate the wrath of their invisible enemies. Though the best hope of the republic was in the valor and conduct of Aurelian, yet such was the public consternation, when the barbarians were hourly expected at the gates of Rome, that, by a decree of the senate the Sibylline books were consulted. Even the emperor himself, from a motive either of religion or of policy, recommended this salutary measure, chided the tardiness of the senate, and offered to supply whatever expense, whatever animals, whatever captives of any nation, the gods should require. Notwithstanding this liberal offer, it does not appear, that any human victims expiated with their blood the sins of the Roman people. The Sibylline books enjoined ceremonies of a more harmless nature, processions of priests in white robes, attended by a chorus of youths and virgins; lustrations of the city and adjacent country; and sacrifices, whose powerful influence disabled the barbarians from passing the mystic ground on which they had been celebrated. However puerile in themselves, these superstitious arts were subservient to the success of the war; and if, in the decisive battle of Fano, the Alemanni fancied they saw an army of spectres combating on the side of Aurelian, he received a real and effectual aid from this imaginary reënforcement.