Cicero to Atticus, written at the Tusculan villa on the evening of 27 May 44 BC — Perseus dateline Scr. in Tusculano vi K. Iun. vesperi a. 710 (44). (The works.yaml entry carries the same day; the launch-prompt date of 28 May appears to conflate it with 15.5.) The letter is the immediate sequel to 15.5: having received the courier from Brutus and Cassius, Cicero has now in fact written to Hirtius, commending the standing of Brutus and Cassius to him, even though he expects little real movement from a man who is already as honourable as Hirtius and who can hardly be improved by Cicero’s authority. He writes to share Hirtius’s response with Atticus.

Section 2 is unusual: Cicero embeds the full text of Hirtius’s reply, opening with its own salutation HIRTIVS CICERONI suo salutem. Hirtius reports that he has himself withdrawn to his Tusculan villa, dismisses any prospect of hurrying back to Rome for the Nones, declares that safeguards have been provided “for so many years ahead,” and urges Cicero to use his influence in the opposite direction from the one Brutus and Cassius expect: not to spur them, but to restrain them from “some hotter design,” since (he says) the present convulsions cannot last of themselves. Section 4 returns to Cicero’s own voice: he has written back assuring Hirtius that the Liberators are considering nothing hotter, and confirms that, just as he was sealing the letter, Balbus reported that Servilia (Brutus’s mother) has returned to Rome and gives her word that the conspirators will not leave Italy. The embedded sub-letter is among the few surviving specimens of Hirtius’s voice in the correspondence.