Sir Richard C. Jebb, Commentary on Sophocles: Electra

μηλοσφαγεῖ … ἱερὰ: cp. 190 “οἰκονομῶ θαλάμους” (n.).

ἔμμην᾽ ἱερά. Every month, on the date of Agamemnon's death, choruses sang paeans, victims were sacrificed to the saving gods, and a banquet (284) followed. Monthly celebrations were frequent in Greece. Thus offerings were made on the Athenian acropolis at each “νουμηνία” ( Her. 8. 41: [Dem. ] or. 25 § 99). There were also “ἐπιμήνια” to Heracles at the Cynosarges (Athen. p. 234 E). At Sparta Apollo was propitiated on the first and the seventh of each month ( Her. 6. 57). Cp. Legg. 828 C “θύοντας τούτων” (“τῶν θεῶν”) “ἑκάστοις ἔμμηνα ἱερὰ χορούς τε καὶ ἀγῶνας μουσικούς”. Lucian Parasit. 15 “αἱ πόλεις...τὰς μὲν δἰ ἔτους τὰς δὲ ἐμμήνους ἑορτὰς ἐπιτελοῦσι”.

τοῖς σωτηρίοις: especially to Zeus “Σωτήρ”, and to Apollo “προστατήριος” (637). Artemis, too, was often worshipped as “σώτειρα” or “σωσίπολις”: but indeed all the greater Olympian deities shared this attribute. Cp. Xen. An. 3. 2. 9“τῷ θεῷ τούτῳ” (Zeus Sôter) “θύσειν σωτήρια..συνεπεύξασθαι δὲ καὶ τοῖς ἄλλοις θεοῖς θύσειν κατὰ δύναμιν”.

Argive tradition placed Agamemnon's death on the 13th of Gamelion (about the end of January). So said ‘the Argive historians’ (“οἱ Ἀργολικοὶ συγγραφεῖς”),— according to an Argive writer named Deinias, who lived about 225 B.C. (Schol. here: Müller, Frag. Hist. vol. III. p. 25.) Possibly, then, the idea of Clytaemnestra's hideous festival may have been suggested to the poet by some actual commemoration of the event in Argolis. There was a cult of Agamemnon in various places,—notably in Laconia. (Cp. Roscher's Lexicon, p. 96.)