Titus Livius (Livy), The History of Rome, Book 1
Benjamin Oliver Foster, Ph.D., Ed.

19. When he had thus obtained the kingship, he¹ prepared to give the new City, founded by force of arms, a new foundation in law, statutes, and observances. [2] And perceiving that men could not grow used to these things in the midst of wars, since their natures grew wild and savage through warfare, he thought it needful that his warlike people should be softened by the disuse of arms, and built the temple of Janus at the bottom of the Argiletum, as an index of peace and war, that when open it might signify that the nation was in arms, when closed that all the peoples round about were pacified. [3] Twice since Numa's reign has it been closed: once in the consulship of Titus Manlius, after the conclusion of the First Punic War; the second time, which the gods permitted our own generation to witness, was after the battle of Actium, when the emperor Caesar Augustus had brought about peace on land and [p. 69]sea.² [4] Numa closed the temple after first securing the³ good will of all the neighbouring tribes by alliances and treaties. And fearing lest relief from anxiety on the score of foreign perils might lead men who had hitherto been held back by fear of their enemies and by military discipline into extravagance and idleness, he thought the very first thing to do, as being the most efficacious with a populace which was ignorant and, in those early days, uncivilized, was to imbue them with the fear of Heaven. [5] As he could not instil this into their hearts without inventing some marvellous story, he pretended to have nocturnal meetings with the goddess Egeria, and that hers was the advice which guided him in the establishment of rites most approved by the gods, and in the appointment of special priests for the service of each.

[6] And first of all he divided the year into twelve months, according to the revolutions of the moon. But since the moon does not give months of quite thirty days each, and eleven days are wanting to the full complement of a year as marked by the sun's revolution, he inserted intercalary months in such a way that in the twentieth year the days should fall in with the same position of the sun from which they had started, and the period of twenty years be rounded out. [7] He also appointed days when public business might not be carried on, and others when it might, since it would sometimes be desirable that nothing should be brought before the people.

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