Recent scholarship has identified Cic. Phil. 2.55 as containing a comparison between Mark Antony and Helen of Troy, designed to highlight Antony’s effeminacy and alleged passive homosexuality, traits purportedly manifest since his youth.Footnote 1 While the analogy with HelenFootnote 2 may carry a comic element, as scholars have noted,Footnote 3 the metrical structure in the last clause of the sentence injects a tragic dimension hitherto unnoticed by scholars:
ut Helena Troianis, sic iste huic rei publicae causa belli, cāusā pēstĭs ātque ēxĭtī fŭīt.
As Helen was to the Trojans, so this fellow was to this Republic, the cause of war, the cause of ruinous destruction.Footnote 4
The rhythmic prose forms a hypodochmius, a less common variant of the dochmius—a clausula par excellence of Greek tragedy—frequently employed in moments of heightened emotional turmoil to convey agitation and despair.Footnote 5 Latin rhythmic prose, including the hypodochmiac clausula, appears to have developed from Hellenistic prose rhythm,Footnote 6 with Hutchinson arguing that Cicero was the first to adopt the Hellenistic rhythmic system.Footnote 7 However, owing to the limited and fragmentary evidence of Latin prose before Cicero, absolute certainty on this point remains elusive.Footnote 8 It seems that Cicero significantly influenced later authors of the Republican and Imperial eras, although some discrepancies are evident.Footnote 9 While Sallust and Livy appear to have deliberately avoided these rhythms, exhibiting markedly different preferences, Tacitus employed the so-called ‘Ciceronian’ rhythmic canon in the Dialogus but refrained from doing so in his historiographical works.Footnote 10 According to statistical analyses by Keeline and Kirby, the highest incidence of hypodochmiac clausulae occurs in Velleius Paterculus’ Historiae and Seneca’s De clementia.Footnote 11 Regarding Cicero, although the use of the hypodochmiac clausula is not widespread, it is by no means rare.Footnote 12 In the Philippics, this clausula appears in several instances, such as at 5.5, where Cicero warns of the dangers of granting Gallia Ulterior to Antony, evoking the spectre of barbarian troops threatening Rome;Footnote 13 at 9.15, where he calls upon the senators to honour and express gratitude to the deceased Sulpicius Rufus for his service to the res publica;Footnote 14 and at 13.21, where Cicero, after introducing several themes of invective, such as ferocitas and immanitas, portraying Antony and his followers as barbarians, and criticizing their disunited conduct towards Rome, the embassy and Cisalpine Gaul, questions whether Lepidus ought to make peace with Antony.Footnote 15 In all these instances, Cicero introduces a tragic tone, reminding his audience of the threat that Mark Antony poses to the Republic.
It is conceivable that Cicero drew upon both Attic and Roman tragic plays, particularly tragedies centred on the Trojan Cycle. Helen’s culpability for the outbreak of the Trojan War was a recurrent theme in Greek tragedy,Footnote 16 notably in the agōn between Hecuba and Helen herself in Euripides’ Trojan Women (914–1035).Footnote 17 Note also Helen’s use of anticategoria in the Trojan Women (particularly in lines 917–65), a rhetorical technique by which an accusation is turned back on the accuser. Cicero employs the same strategy in Phil. 2.19, 21, 34, 39, 74–5, and it can be argued that he uses it in the present context too. In this passage, Cicero not only accuses Antony of having instigated the Civil War in 49 b.c. but also defends himself against the accusation made by the consul of 44, who blamed Cicero for the rupture between Pompey and Caesar.
It is also possible to include a fragment preserved by Cicero in Diu. 1.42,Footnote 18 commonly attributed to Ennius’ lost tragedy Alexander,Footnote 19 which exhibits language strikingly similar to that in Phil. 2.55:
Apollo with foretelling voice gave forth that Priam should forbear to take up the first boy who should be born to him after that; that the boy would be a ruin to Troy, a plague to Pergamum.Footnote 20
The lexical and thematic parallels between the Ennian fragment and the passage of Cicero suggest that Ennius may have been Cicero’s source for Phil. 2.55. These shared elements further reinforce the relationship between the hypodochmiac clausula in Cicero and the tragic framework of the passage.
Other tragic sources may also inform our understanding of the passage. For instance, Seneca’s Trojan Women (892) employs language that echoes both the Ennian and the Ciceronian fragments, presenting Helen as the source of the Greeks’ and Trojans’ destruction (Sen. Tro. 891–2):

Can anyone hesitate to enter on a marriage that Helen advocates? You plague, you ruin, you scourge.Footnote 21
Thus, considering these reflections and the context of Cicero’s use of the hypodochmiac clausula, it is reasonable to infer that he aimed to reinforce the tragic argument in this passage about Antony, drawing on established themes from Attic and Roman tragedy.
In conclusion, Cicero underscores two key elements: Antony’s degeneracy, evident since his youth, which renders him unfit to govern the res publica; and the theatrical dimension, beginning with the comic image of Antony dressed as Helen and culminating in the use of a hypodochmiac clausula at the end of the sentence. This clausula introduces a tragic atmosphere, drawn from tragic sources, and reminds the audience that, just as in 50/49, Antony would once again instigate a civil war.Footnote 22