By the advocates of the w sound of the v much stress is laid upon the fact that the poets occasionally change the consonant into the vowel u, and vice versa; as Horace, Epode VIII. 2:
“Nivesque deducunt Jovem, nunc mare nunc siluæ̈;”
Or Lucretius, in II. 232:
“Propterea quia corpus aquae naturaque tenvis.”
Such single instances suggest, indeed, a common origin in the u and v, and a poet’s license, archaistic perhaps; but no more determine the ordinary value of the letter than, say, in the English poets the rhyming of wĭnd with mīnd, or the making a distinct syllable of the ed in participle endings.
Another argument used in support of the w sound is taken from the words of Nigidius Figulus.
He was contending, we are told, that words and names come into being not by chance, or arbitrarily, but by nature; and he takes, among other examples, the words vos and nos, tu and ego, tibi and mihi:
[Aul. Gell. X. iv. 4.] Vos, inquit, cum dicimus motu quodam oris conveniente cum ipsius verbi demonstratione utimur, et labias sensim primores emovemus, ac spiritum atque animam porro versum et ad eos quibuscum sermonicamur intendimus. At contra cum dicimus nos neque profuso intentoque flatu vocis, neque projectis labiis pronunciamus; sed et spiritum et labias quasi intra nosmetipsos coercemus. Hoc idem fit et in eo quod dicimus tu et ego; et tibi et mihi. Nam sicuti cum adnuimus et abnuimus, motus quidem ille vel capitis vel oculorum a natura rei quam significabat non abhorret; ita in his vocibus, quasi gestus quidam oris et spiritus naturalis est.
But a little careful examination will show that this passage favors the other side rather.
The first part of the description: “labias sensim primores emovemus,” will apply to either sound, vos or wos, although better, as will appear upon consulting the mirror, to vos than to wos; but the second: “ac spiritum atque animam porro versum et ad eos quibuscum sermonicamur intendimus,” will certainly apply far better to vos than to wos. In wos we get the “projectis labiis” to some extent, although not so marked as in vos; but we do not get anything like the same “profuso intentoque flatu vocis” as in vos.