Cicero to Atticus, written at the gates of Rome on the night before, or before dawn on, 18 January 49 BC (the manuscript dateline: Scr. ad urbem xiv sub noctem aut xiiii ante lucem in K. Febr. a. 705 (49)). This is the famous subito consilium cepi letter — the moment of decision recorded as Cicero leaves the City, on the news that Caesar has crossed into Italy. Chronologically it opens the Rubicon-week sequence in book 7: the southward retreat through Latium and Campania that the next four letters carry forward to Formiae, Minturnae, and Cales.

The letter is one paragraph and almost all breath. The decision (subito consilium cepi, “on a sudden I have decided”) is stated and at once qualified by its motive (the laurelled lictors of his unsought triumph, which would draw the eye and the gossip). He does not know what to do; he does not know what Pompey is doing; he is asking Atticus for counsel while waiting for Atticus’s own. The two key clauses land as antitheses: omnes, si in Italia consistat, erimus una; sin cedet, consili res est — if Pompey stands in Italy they all stand with him, but if he gives way the question reopens. The closing imperative is the characteristic Ciceronian appeal in extremity: crebro ad me scribe vel quod in buccam venerit, write to me often, even whatever first comes to mind.