Also known as: Septḗrion, Septaria, or Septirion, or Steptirion, or Stepirion.
Σεπτήριον derives from the verb σέβω which originally meant 'to withdraw' $^{69}$.
Septḗrion is a purification and atonement festival. It is part of a sequence of festivals and rituals that take place every 8 years in late spring to early summer. It is linked to the Pythian games, as it’s said that the laurels cut at Tempe were awarded to the games victors. However, since the Pythian games are held every 4 years, this tradition must take place only every second Pythian games.
Every 8 years. Chronologically, it falls before the festivals of Heroïs, and Daphnephoria but exact dates are unknown. If the Daphnephoria falls on the 7th of the month following the Acronychal rising$^{67}$, then this festival must fall sometime before that. Perhaps at the same time as the Acronychal rising elsewhere in Greece, when the Daphnephoros is thought to cut the laurel in Tempe for his return $^{68}$. This would place it two weeks before the Daphnephoros, on the 23rd of Ilaios | Ιλαίος (the same date provided on this website $^{42}$).
The Laurels cut are said to have been awarded to victors of the Pythian games. This must mean that the Septerion aligns to the years in which the Pythian games are held. The games - running on a 4 year schedule since Classical times - are held in the third year of each Olympiad (i.e. 2023, then 2027, etc)
<aside> <img src="/icons/hourglass_pink.svg" alt="/icons/hourglass_pink.svg" width="40px" /> More on the timing of The Great Year
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During the festival, a child of aristocratic origin - whose parent are both alive - impersonates Apollon and leads a procession to the sanctuary of Apollon at Delphi. The child sets fire to a wooden structure beneath the temple of Apollon, which is said to symbolise the dwelling of Python.
He is then led in a procession to the Thessalian Tempe valley, where he undergoes a ritual cleansing and makes accompanying sacrifices in the river Peneius.
Apollo, being a boy, when he overpowered the snake at Pytho, washed his hands in the Peneius . . . and cutting the laurel which was lying beside him he put it round [his head]
– Callimachus, Aetia $^{65}$
The central element of the festival is the plucking of a laurel branch from Tempe, which the previous boy carries in a celebratory procession home to Delphi, while the current one remains to serve in Tempe for 8 years - returning home at the Daphnephoria festival in his 9th year.
A Delphic boy served at Tempe on a nine-year cycle, replaced each cycle by the boy sent out at this festival. During Septḗrion a boy is escourted along the sacred road (Plut. Quaest. Gr. 12) between Delphi and Tempe to serve his term in the temple. They stop at the village of Deipnias for a meal, as this was the place where Apollon ate after leaving the Tempe valley. This may be referenced by Callimachus in the Aetia:
Fr. 87: Δειπνιὰς ἔνθεν μιν δειδέχαται
From there Deipnias received him
– Callimachus, Aetia $^{64,}$$^{65}$
In the ninth year, at the festival of Daphnephoria the boy cuts branches from the sacred laurel, crowns himself and returns in a procession to Delphi; carrying a cutting of the laurel from Tempe. His return is celebrated with cheerful songs sung by choruses of unmarried girls. The laurel is then used to make wreaths for the winners of the Pythian Games, demonstrating the special holiness of the Tempe laurel in the cult of Apollo at Delphi.
[…]
Purged in the Vale of Tempe by the will of Zeus on high, helped by Pallas on your way to Pytho, o Apollo, you talked Earth, the flower-nurse, and Themis of the lovely hair, into giving you the perfumed seat of power, o Apollo.
So, as gods know gratitude, you grant Athena pride of place at the threshold of your holy temple, o Apollo: you thank her for her kindness, the kindness she showed long ago you remember always; sumptuous is her honour, o Apollo.
The gods make generous donations: Poseidon a most religious site, the Nymphs a grotto called Korykian, o Apollo, Dionysos torch-lit mountain revels. Stem Artemis patrols the land with her well-trained pack of guard-dogs, o Apollo.
[…]
– Aristonoos of Corinth, Hymn to Pythian Apollon