[4] Titus Livius (Livy) and Plutarch refer to the story that Numa was instructed in philosophy by Pythagoras, but discredit it as chronologically and geographically implausible.

In Plutarch and Livy's account, Numa, after being summoned by the Senate from Cures, was offered the tokens of power amid an enthusiastic reception by the people of Rome.

In addition to the endorsement by Jupiter, he is supposed to have had a direct and personal relationship with a number of deities, most famously the nymph Egeria, who, according to legend, taught him to be a wise legislator.

According to Livy, Numa claimed that he held nightly consultations with Egeria on the proper manner of instituting sacred rites for the city.

About half of these books—Plutarch and Livy differ on their number—were thought to cover the priesthoods he had established or developed, including the flamines, pontifices, Salii, and fetiales and their rituals.

After securing peace with Rome's neighbours, the doors of the temples were shut[15] and remained so for the duration of Numa's reign, a unique case in Roman history.

[22] In a somehow comparable,[23] more moral rather than legal fashion, Numa sought to associate himself with one of the roles of Vegoia in the religious system of the neighbouring Etruscans, by deciding to set the official boundaries of the territory of Rome, which Romulus had never wanted, presumably with the same concern of preserving peace.

Numa also established the office and duties of Pontifex Maximus and instituted (Plutarch's version[25]) the flamen of Quirinus, in honour of Romulus, in addition to those of Jupiter and Mars that already existed.

Livy and Dionysius give a largely concordant picture of the vast founding work carried out by Numa concerning Roman religion and religious institutions.

Cetera quoque omnia publica privataque sacra pontificis scitis subiecit, ut esset quo consultum plebes veniret, ne quid divini iuris negligendo patrios ritus peregrinosque adsciscendo turbaretur.

Nec celestes modo caerimonias sed iusta quoque funebria placandosque manes ut idem pontificem edoceret, quaeque prodigia fulminibus a Iove quo visu missa susciperentur atque curarentur.

He also placed all other religious institutions, public and private, under the control of the decrees of the pontiff, to the end that there might be some authority to whom the people should come to ask advice, to prevent any confusion in the divine worship being caused by their neglecting the ceremonies of their own country, and adopting foreign ones.

He further ordained that the same pontiff should instruct the people not only in the ceremonies connected with the heavenly deities, but also in the due performance of funeral solemnities, and how to appease the shades of the dead; and what prodigies sent by lightning or any other phenomenon were to be attended to and expiated.

[27]Livy lists the hostiae, victims, as the first competence of the pontiffs: following this come the days, temples, money, other sacred ceremonies, funerals and prodigies.

Livy continues saying Numa dedicated an altar to Jupiter Elicius as the source of religious knowledge, and consulted the god by means of auguries as to what should be expiated; he instituted a yearly festival to Fides (Faith) and commanded the three major flamines to be carried to her temple in an arched chariot and to perform the service with their hands wrapped up to the fingers, meaning Faith had to be sacred as in men's right hand; among many other rites he instituted he dedicated places of the Argei.

[14] Plutarch in his Parallel Lives mention that Numa Pompilius made January the first month in the calendar instead of March by the next reason: "he wished in every case that martial influences should yield precedence to civil and political.

For this Janus, in remote antiquity, whether he was a demi-god or a king, was a patron of civil and social order, and is said to have lifted human life out of its bestial and savage state.

(Plutarch) William Blackstone says that Numa may be credited with "originally inventing" corporations: "They were introduced, as Plutarch says, by Numa; who finding, upon his accession, the city torn to pieces by the two rival factions of Sabines, and Romans, thought it a prudent and politic measure, to subdivide these two into many smaller ones, by instituting separate societies of every manual trade and profession.

According to Plutarch, he divided the existing land among indigent people in Rome, and persuaded them to work in agriculture, thinking it would reduce aggressivity, and eliminate poverty and consequently crime.

[36] According to Plutarch, Numa permitted slaves to feast with their masters during the Saturnalia, for "admitting to the enjoyment of the yearly fruits of the earth those who had helped to produce them".

Making the Romans more peaceful was one of his main targets from the beginning of the kingship and many of his actions were directly or indirectly intended to achieve this aim.

He succeeded so much that the situation was even better than described in the song: "And on the iron-bound shield-handles lie the tawneyº spiders' webs"; "rust now subdues the sharp-pointed spears and two-edged swords; no longer is the blast of brazen trumpets heard, nor are the eyelids robbed of delicious sleep."

Plutarch put this in contrast to the policies and the destiny of his predecessors and successors: Romulus who is depicted as war-king and the 5 kings after him, from which 4 were killed and 1 dethroned and expelled from Rome.

When Petilius after the advice of his friends opened it, the one that was inscribed with the name of the king was found empty, the other containing two bundles each of seven books, not complete but looking very recent, seven in Latin dealing with pontifical law and seven in Greek of philosophy as it was in that remote past.

[46] The Christian philosopher Clement of Alexandria in his book Stromata claimed that King Numa Pompilius was influenced by Mosaic law, and due to this refrained from making human images in sculpture.

"[48] In a similar manner, the Coptic monophysite bishop John of Nikiû likened Empress Theodora, consort of Justinian, to four prominent figures of Roman history (Romulus, Numa, Caesar, Augustus), citing her reforms aimed at eradicating prostitution.