C.S. Lewis's Lost Aeneid: Arms and the Exile

Started reading the recently published C.S. Lewis's Lost Aeneid: Arms and the Exile (ed. A.T. Reyes). Lewis begins his translation of the Aeneid with four unfamiliar lines that according to the introduction are lines that did not appear til (or at least, that there is no recording of until) the 9th century.

"Ille ego, qui quondam gracili modulatus avena

carmen, et egressus silvis vicina coegi

ut quamvis avido parerent arva colono,

gratum opus agricolis: at nunc horrentia Martis

***

Arma virumque cano..."

"Lo I am he who led the song through slender reed to cry

And then, come forth from out the woods to hide, the fields that are thereby

In woven verse I bade obey the hungry tillers' need:

Now I, who sang their merry toil, sing Mars and dreadful deed.

***

Of Arms and a Man I sing..."