How the legend originated cannot now be ascertained; but we may easily imagine several ways in which it might have originated; nor is it at all necessary to suppose, with Julius Frontinus, that two young men were dressed up by the Dictator to personate the sons of Leda. It is probable that Livy is correct when he says that the Roman general, in the hour of peril, vowed a temple to Castor. If so, nothing could be more natural than that the multitude should ascribe the victory to the favor of the Twin Gods. When such was the prevailing sentiment, any man who chose to declare that, in the midst of the confusion and slaughter, he had seen two godlike forms on white horses scattering the Latines, would find ready credence. We know, indeed, that in modern times a very similar story actually found credence among a people much more civilized than the Romans of the fifth century before Christ. A chaplain of Cortes, writing about thirty years after the conquest of Mexico, in an age of printing presses, libraries, universities, scholars, logicians, jurists, and statesmen, had the face to assert that, in one engagement against the Indians, St. James had appeared on a gray horse at the head of the Castilian adventurers. Many of those adventurers were living when this lie was printed. One of them, honest Bernal Diaz, wrote an account of the expedition. He had the evidence of his own senses against the legend; but he seems to have distrusted even the evidence of his own senses. He says that he was in the battle, and that he saw a gray horse with a man on his back, but that the man was, to his thinking, Francesco de Morla, and not the ever-blessed apostle St. James. "Nevertheless," Bernal adds, "it may be that the person on the gray horse was the glorious apostle St. James, and that I, sinner that I am, was unworthy to see him." The Romans of the age of Cincinatus were probably quite as credulous as the Spanish subjects of Charles the Fifth. It is therefore conceivable that the appearance of Castor and Pollux may be become an article of faith before the generation which had fought at Regillus had passed away. Nor could anything be more natural than that the poets of the next age should embellish this story, and make the celestial horsemen bear the tidings of victory to Rome.