The ghost of Darius provides a versified history of the Persian kingship, from the beginning down to the reign of his luckless son Xerxes, that starts out as follows in Martin West's Teubner text (1990):

First comes ‘the Mede Cyaxares, whom A[eschylus] probably saw as the first king of a united Media and Persia, and therefore the right person to begin his list’.Footnote ¹ Unless ἄλλος (766) is corrupt,Footnote ² the first two members of the dynasty are anonymous. This is not perhaps surprising, given Aeschylus’ limited knowledge of early Median and Persian history and given his use of these rulers as foils to the blest (εὐδαίμων) Cyrus. Each of them is, like the equally anonymous Cambyses (773), accorded only one or two lines, in contrast to the five lines devoted to Cyrus the Great. What is surprising is that the second of these is singled out for his good sense and his restraint (‘For his clear thinking plied the tiller of his passions’, 767).Footnote ³ Further, it is not clear what point is being made by attributing ‘this deed’ (τόδ’ ἔργον, 766) to the good sense and restraint of the son of the Mede, particularly since it is not immediately apparent to what deed reference is being made.Footnote ⁴ As Alexander Garvie notes in his recent commentary on the play, ‘That this line [767] is out of place in the codd. is highly likely’.

Denys Page therefore proposed relocating the line to follow 769.Footnote ⁵ This is an improvement, as the laudatory comment seems much more appropriate as a characterization of Cyrus, whose good sense and restraint can now be seen as accounting for his ability to impose peace on all his friends (769). An earlier attempt had been made to transpose line 767. The scholia vetera to the line, identifying as Artaphrenes the unnamed ruler whose good sense and restraint are commended, claim that the line presents an etymology of the ruler's name: ὁ Ἀρταϕέρνης, ὃν ἐτυμολογεῖ, ὁ ἀρτίας ἔχων ϕρένας.Footnote ⁶ Since Artaphrenes is not named here, but is named later in the text, at line 776 and again in the interpolated line 778, Carl Gottfried Siebelis relocated 767 to follow 776.Footnote ⁷ Dirk van Nes, although preferring to leave the line in its transmitted place, notes that, if etymologizing is at issue here, the line would better follow 777.Footnote ⁸ Aeschylus is indeed fond of explicating and etymologizing proper names,Footnote ⁹ but good sense and restraint are odd qualities to highlight when describing the conspirator who carried out an assassination using guile (σὺν δόλῳ … ἔκτεινεν, 775–6). In any event, the scholion seems to reflect a text in which line 767 stood neither immediately before nor immediately after line 777, as its wording suggests that it is identifying someone not named in the text.

I should like to propose that the ϕρένες in line 767 have nothing to do with Artaphrenes' name, that the word refers rather to the good sense of Cyrus and that the line originally stood after line 772, thus:

That is, the line is Darius' explanatory (γάρ) gloss on εὔϕρων in the previous line. Cyrus' success in bringing peace and expanding the Persian empire is owed to the gods' affection for him, whom they approve because he is sensible. Aeschylus is inordinately fond of playing on the relationship between ϕρένες and words containing the element ϕρον- or -ϕρων. So, in Septem, Eteocles praises Amphiaraus for being, among other things, σώϕρων (610), but immediately accounts for his participation in the enemy attack as involuntary (βίᾳ ϕρενῶν, 612). Following his matricide, Orestes admits that he is losing control of his phrenes, so he makes sure to proclaim the justice of his act while he is still ἔμϕρων (Cho. 1024–6). Earlier in the same play Orestes' nurse noted that her job entails the application of a nurse's phren in order to correct the senselessness (τὸ μὴ ϕρονοῦν) of her infant charge (754–5). Shortly afterwards, when the chorus instruct the nurse to summon Aegisthus with cheerful phren (772), despite the apparently sad news regarding the fate of Orestes, she replies by asking incredulously whether the chorus are themselves cheered by the news (ἦ ϕρονεῖς εὖ; 774). In Agamemnon, the chorus attribute Clytaemestra's arrogant words (περίϕρονα ἔλακες, 1426) to the fact that her phren (1427) has been maddened by the blood she has just shed. Earlier, the chorus had described Agamemnon's change of thinking at Aulis (ϕρονεῖν μετέγνω, 221) in terms of a wind-shift in his mind (ϕρενὸς … τροπαίαν, 219).Footnote ¹⁰

The word εὔϕρων specifically is associated with the workings of the phrenes on two occasions in Aeschylus. In Supplices, the Argive king acknowledges that it is not sensible (εὖϕρον, 378) to rebuff the chorus's prayers, but he is at a loss, since his phrenes are gripped by dread (379). Of particular interest in connection with the passage we have been considering (Persae 767) is Agamemnon 805–6:

Here the chorus, addressing their victorious king on his homecoming, assure him that their kindly disposition toward their successful returning leader derives not from the mere surface of their phren but, it is implied, from the very depths of their feelings. Shortly before, they had flattered Agamemnon by suggesting that he was too discerning to be deceived by dissemblers, whose pretence of friendship only gives the appearance of coming from a kindly disposed mind (εὔϕρονος ἐκ διανοίας, 797). Unlike them, the chorus are willing to admit frankly that they earlier had reservations about Agamemnon's campaign to retrieve the unfaithful Helen, saying that they felt he was not plying the tiller of his thoughts aright (οὐδ᾿ εὖ πραπίδων οἴακα νέμων, 802), using the very same metaphor we see in Persae 767.Footnote ¹¹

If, then, line 767 originally stood between lines 772 and 773,Footnote ¹² the ghost of Darius is, as it were, defining τὸ εὖϕρον as having one's phrenes in control of one's thymos, in contrast, say, to possessing the σιδηρόϕρων θυμός (Septem 52) that characterizes the savage attackers of Thebes or the implacable thymos that Electra claims to have inherited from her mother and which she likens to a bloody-minded wolf (λύκος γὰρ ὥστ᾿ ὠμόϕρων | ἄσαντος ἐκ ματρός ἐστι θυμός, Cho. 421–2).Footnote ¹³ There is no reason to object to the appearance of γάρ in successive sentences, for which the text of Aeschylus affords a number of parallels.Footnote ¹⁴ I can supply no convincing explanation for the dislocation of the line, although the similarity in the endings of consecutive lines (-στρόϕουν 767, στρατόν 773) may have caused the omission of 767. In any event, it is as likely to have fallen out from after 772 as after 769 (Page), 776 (Siebelis) or 777 (van Nes). The manuscripts of the tragedians provide several examples of lines omitted in cases where no obvious palaeographical explanation (homoioteleuton, homoioarkton, vel sim.) is available, in some instances the line being inserted later in the margin or at the foot of the page.Footnote ¹⁵ On at least two occasions, however, the omitted line and the line preceding it have identical words in the middle of the verse in the same metrical sedes, as 772 and 767 have γάρ. So, the scribe of Vat. gr. 1345 initially omitted Eur. Phoen. 9 (ϕῦναι λέγουσιν, ἐκ δὲ τοῦδε Λάιον; line 8 reads Πολύδωρον ἐξέϕυσε, τοῦ δὲ Λάβδακον), later adding it, in the correct place, between the lines. And the scribes of both Madrid 4677 and Leiden Voss. gr. Q4A omitted PV 515 which, curiously enough, ends in οἰακοστρόϕος (τίς οὖν ἀνάγκης ἐστὶν οἰακοστρόϕος; line 514 reads τέχνη δ’ ἀνάγκης ἀσθενεστέρα μακρῷ), the former adding it in the margin while, in the latter manuscript, the line was added between the lines by a later hand.