Varro
Marcus Terentius Varro, Rome's greatest scholar, whose explanations of the month names Censorinus follows.
116–27 BCE
How the Romans fixed the year
Censorinus, On the Birthday 20–22 (238 CE), in the edition of Friedrich Hultsch (Leipzig, 1867) · 238 CE
de quibus omnibus disserere quoniam longum est, ad Romanorum annum transibimus. Annum vertentem Romae Licinius quidem Macer et postea Fenestella statim ab initio duodecim mensum fuisse scripserunt: sed magis Iunio Gracchano et Fulvio et Varroni et Suetonio aliisque credendum, qui decem mensum putarunt fuisse, ut tunc Albanis erat, unde orti Romani.
It would take too long to discuss all of these, so I will move on to the year of the Romans. Licinius Macer, and later Fenestella, wrote that the year at Rome had twelve months from the very beginning. But we should rather believe Junius Gracchanus, Fulvius, Varro, Suetonius and others, who thought it had ten months. So it was at that time among the Albans, from whom the Romans came.
Varro autem Romanos a Latinis nomina mensum accepisse arbitratus auctores eorum antiquiores quam urbem fuisse satis argute docet.
But Varro held that the Romans took the names of the months from the Latins. He shows quite cleverly that those who made the names were older than the city.
Where the months got their names
Macrobius, Saturnalia 1.12–14 (early fifth century CE), in the edition of Franz Eyssenhardt (Leipzig, 1893) · early fifth century CE; the dialogue is set in the 380s
Cingio etiam Varro consentit adfirmans nomen Veneris ne sub regibus quidem apud Romanos uel Latinum uel Graecum fuisse, et ideo non potuisse mensem a Venere nominari.
Varro agrees with Cingius. He states that the Romans did not know the name of Venus, in Latin or in Greek, even in the time of the kings, and so the month could not have been named after her.