They settled down at that time to an orderly life through their own efforts, when once they had gained faith in the divine; after which they continued at peace both with one another and with the outside tribes throughout the entire reign of Numa. He, no less than Romulus, seemed to have been provided for them by divine guidance; indeed, men who know Sabine history best declare that he was born on the same day that Rome was founded. In this way because of both of them the city quickly became strong and well ordered; for the one gave it practice in the arts of warfare, — of necessity, since it was but newly founded, — and the other taught it, in addition, the arts of peace, so that it became equally distinguished in each.
Cadrenus I, p. 259 f.
Thus, then, through both of them the city quickly became strong and well ordered; for Numa shaped its political and peaceable institutions, even as Romulus determined its military career.
Cedrenus I, p. 295.
Dio the Roman says that Janus, an ancient hero, because of his entertainment of Saturn, received the knowledge of the future and of the past, and that on this account he was represented with two faces by the Romans. From him the month of January was named, and the year takes its beginning from this same month.