Macrobius, Saturnalia 6.19-26
Vetius Agorius Praetextatus narrates the humorous origin of his cognomen:
“In the past, it was the custom for senators to enter into the curia with their sons who wore the toga praetexta. Whenever a discussion was held upon a great matter in the senate, and had to be extended into the next day, it was agreed that no one would say anything publicly about the matter which they had discussed until it had been formally announced. The mother of a boy named Papirius, who had been in the curia with his father, asked her son what the Senators had done that day. The boy responded that the matter must be kept quiet, and was not his to divulge. The mother became even more desirous of hearing: the secrecy of the affair and the silence of the boy goaded her soul on to asking further, so she began to make more pressing and vigorous inquiry. At last, because his mother urged him so, the boy contrived a deceitful jest: he said that it had been discussed in the senate whether it would be better for the Republic if one man took two wives, or if one wife were shared among two men.
When the mother heard this, her very soul went pale: she left the house trembling, and brought the news to other married women. On the following day, great crowds of mothers flocked together before the senate. Crying and pleading, they begged that one woman be married to two men, rather than that one man take two wives. As they entered the senate, the senators wondered what this wildness was, and what the mothers wanted. They feared that the shameless frenzy of the modest sex was a portent of no minor affair. The boy Papirius then took away all fear. He walked into the middle of the curia, and narrated what his mother had insisted on hearing and what he had told her, exactly as it had happened. The senate applauded his faith and brilliance, and issued a decree that subsequently no boys should enter the senate with their fathers, with the exception of Papirius alone. Afterward, the name of Papirius was granted to him as an honorific title, on account of his discretion in knowing when to speak and when to remain silent even at the age when he still wore the toga praetexta. This cognomen afterward remained in our family.
The Scipios received their name in a similar way, because Cornelius, who helped to guide his blind father like a rod, was given the name Scipio which he bequeathed to his posterity. Thus, Avienus, is your Messala named from the cognomen of that Valerius Maximus who, after he captured the Sicilian city Messana, was awarded the cognomen of Messala.”
Mos antea senatoribus fuit in curiam cum praetextatis filiis introire. Cum in senatu res maior quaepiam consultabatur eaque in posterum diem prolata est, placuit ut hanc rem super qua tractavissent ne quis enuntiaret priusquam decreta esset. 20 Mater Papirii pueri, qui cum parente suo in curia fuerat, percontatur filium quidnam in senatu egissent Patres. Puer respondit tacendum esse, neque id dici licere. Mulier fit audiendi cupidior: secretum rei et silentium pueri animum eius ad inquirendum everberat: quaerit igitur conpressius violentiusque. 21 Tum puer urgente matre lepidi atque festivi mendacii consilium capit. Actum in senatu dixit, utrum videretur utilius magisque e re publica esse, unusne ut duas uxores haberet, an ut una apud duos nupta esset. 22 Hoc illa ubi audivit, animo conpavescit: domo trepidans egreditur: ad ceteras matronas adfert: postridieque ad senatum copiosae matrumfamilias catervae confluunt. Lacrimantes atque obsecrantes orant, una potius ut duobus nupta fieret quam ut uni duae. 23 Senatores ingredientes curiam quae illa mulierum intemperies et quid sibi postulatio isthaec vellet mirabantur, et ut non parvae rei prodigium illam verecundi sexus inpudicam insaniam pavescebant. Puer Papirius publicum metum demit. 24 Nam in medium curiae progressus, quid ipsi mater audire institisset, quid matri ipse simulasset, sicuti fuerat, enarrat. 25 Senatus fidem atque ingenium pueri exosculatur, consultumque facit uti posthac pueri cum patribus in curiam ne introeant praeter illum unum Papirium. Eique puero postea cognomentum honoris gratia decreto inditum Praetextatus, ob tacendi loquendique in praetextata aetate prudentiam. 26 Hoc cognomentum postea familiae nostrae in nomen haesit. Non aliter dicti Scipiones, nisi quod Cornelius qui cognominem patrem luminibus carentem pro baculo regebat Scipio cognominatus nomen ex cognomine posteris dedit: sic Messala tuus, Aviene, dictus a cognomento Valerii Maximi qui, postquam Messanam urbem Siciliae nobilissimam cepit, Messala cognominatus est.