1–18

The eighteen lines of proem to the fourth book of the Fasti, which opens the second quarter of the year (or second half of O.'s sixmonth poem), are designed to recall but mark with significant differences both the proem of book 1, composed to introduce the whole year, and the proem of the preceding month of March, addressed to Venus' consort, Mars, joint ancestor of Romulus and protector of his people.

Thus 4.11–12 repeats the opening couplet of book 1, indicating the contents of the Fasti, with two changes: the future canam of 1.2 has become present cano, since O. is now in progress through the year, and the second half of 4.11 substitutes the corresponding part of 1.7 annalibus eruta priscis for the reference in 1.1 to the Latin calendar year. It is now the occasions, tempora, not the rituals, sacra, that are described as retrieved from ancient annals.

But while the proem to book 1, in its re-edited version, was dedicated to the mortal prince and patron Germanicus (and answered by the proemiac address to Caesar in book 11) the proems to books III and IV are addressed to the gods after whom, as O. will argue, the months are named. Mars, the mythical father of Romulus, won apotheosis for his son (2.481–90, imitating the treatment of the same deification in Ennius, Annales 1), but Venus' link with Romulus was more obscure; although she had been the consort of Mars, by whom she gave birth to Amor (Cupid), the ancestry of Romulus had to be traced through her mortal son Aeneas, whose descendant Ilia was impregnated by Mars to produce the twins Romulus and Remus.