The Sidh: Origin

The Danann's Tuatha reigned until the arrival of the fifth and last race of invaders, the sons of Mil or Goidels (or even Gaëls), named after their legendary chief Mil Espaine. The Milesians came for two reasons: the first to avenge the death of Ith, Mil's grandfather who had come to Ireland with all his crew. The second was that the Druids had told them that Ireland was their promised land.
The land where they landed was, at that time, governed by the three grandsons of dagda and their wives Banba, Fotla and Eriu, all three goddesses of suzerainty. The three reigning families were debating the division of the country when the Milesians presented themselves at the mouth of the Boyne and ordered the Dannans to deliver the island to them.

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After a fatal battle with the three kings, a compromise was reached: the Milesians would reign on the visible part of the world, while the Tuatha De Danann would reign on the Other World, invisible part located below the ground. The Dananns therefore had to take refuge in the bowels of the earth. They settled their homes in dolmens and mounds, under the hills and in glass palaces at the bottom of lakes and oceans.
All of these habitats constitute the Other World, the wonderful world of happiness and peace that the Irish call "Sidh". But the Other World is also located on the other side of the ocean where there is neither suffering nor evil, where everything is beautiful and pure. In the Gaelic tradition, it bears the names of "Tir Nan-Og" (the land of the young), "Tir na m-Beo (the land of the living)," Madg Meld "(the plain of joy)," Trir Tairngire "(the land of happiness)," Mag Mor "(the great plain)," Tirr Aill "(the other world) or finally" Tir na ù-Ban "(the land of women).
Ireland was thus left in the hands of the Milesians and their descendants, the Gaels.

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If the gods can come and wander as they please in the human world, the reverse is only rarely possible. Only heroes, exceptional beings, such as Cúchulainn, Conle or Bran Mac Febail have the privilege of visiting and staying in the Sidh, generally at the invitation of a Bansidh. Eternal in essence, every man who enters it cannot return to the human condition. So these men who believe they spend a few hours or a few days in the company of the gods and stay there for several centuries. When they return home, they fall to dust because they are long dead. The period of Samain (New Year of the Celts, around November 1) is conducive to the opening of sidh.

Sidh, the other world

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The etymology of this word means “Peace” in Celtic and, by extension, “paradise”, Vindomagos gwenva in Breton.
The Germanic word Seidhr means magic and designates the science of Freyja la Vane, science which she learned with the Ases because magic is first of all the science of the evocation of the dead ancestors, of their spirit “good” (what is said Manes for a Roman).
This shamanic art of evoking the dead was however prohibited among the Ases and Wotan alone practiced it as High Priest of the Ases. But Sidr would be the most appropriate term to translate our word “religion”, a concept that did not exist among the German-Scandinavians: they were “connected” by their beliefs and their rites…

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Siden in Old English still meant “magic” but, it now has a derogatory meaning, because post evangelical. Belonging to the family of “sacred earthworks” (rath in English), these are the mounds of the founding ancestors.
In Lapland an altar is said seid, which is also the "sacred stone" among the Greeks and they look so much like Sidh that we can only bring them closer to the Celtic rite of the sacrifice of the firstfruits to the Gods which is done on the table of the old dolmen of our megalithic ancestors, which often has cups.
In Sardinia, the eponymous god is Sardus pater and the Sardinians say that he is descended from Sid, "a Punic deer deity honored by the hunters in Antas".

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Many Hindu terms contain the same root, let us quote: Siddhapura, which is a mythical city “beyond the seas” and which is “the city of the perfect” (The Site of fire, the Pharos phrison, or the Site of the Purs ); siddhis which are “higher levels of consciousness” or “(so-called) magical powers” obtained by the practice of Yoga, and also saddhus which are wandering monks

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In Celtic Mythologies, it is said that the Sidhs open on Samhain night to allow everyone to communicate with the Manes of the great ancestors who founded the clan (the “good” Halloween spirits).
In poetic language, the Sidh is compared to the great Mag Meld plain, “the pleasure plain”, or the “land of women”, the “land of youth Og or Oc” Tir na n'og, the “land of promise ”or“ land of the living ”, and“ land of the fairies ”: we can see very well the parallels between Sidh, Paradise and Sunken World, that is to say the Other World, the Beyond: the Water of there, in the “language of birds” practiced by troubadours:
"The Other World has nothing to do with its infernal interpretation proper to monotheism since it includes both the World of the Gods (submerged), that of the Spirits and that of the Dead Ancestors. Difficult to say then if this“ Other World ”is located in the bowels of the earth or above our heads."

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"Sidh is the visible part of the Other World ... We can also locate them in the Islands, beyond the Ocean ... And all divinity occupies a Sidh which, by its nature, is outside of time and space and opens each Night of Samhain… "
This explains why our Bretons call them “Tertre aux Fées”. We have seen, in fact, that if the bodies of ancestors or dead children are buried or cremated, their spirit soars to the sky “in the sun” through a bird: Sacred Crane of the Friesians / Swan of the Germans of the forest / Stork of the Alsatians or the Gallic lark alauda. Likewise, it is this “bird” that will bring back the spirit of the genos / clan when the newborn is born. "

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"The scribe who copied the tale of Cuchulainn and the fairy Fann concludes with these words:" This is the story of the destruction of Cuchulainn by the people of the Sid (residence of spirits). For the power of the demons was great before the Faith (Christian), and it was such that the demons then fought bodily against men and revealed to them wonders and mysteries; and it was believed that they were immortal. And these are the ghosts that the ignorant call Sîd (spirits ) and aes sîde (gent du Sîd) ”.
Skuthi / Skythia is, among the Irish, one of the names of the Other World, which we will bring closer to the Scythia of the Greeks which was probably the archaic matrix of these Celts “scouts” - scouts in English - who, after their “ great trek ”, settled in the Pontic region. Let us therefore note a probable kinship between Sidh, Scythe and Celte / (s) Kelt / Kelt…

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But the “dark” root, scâth, is found in the mythological character Scâthach “l'ombreuse” as in that of Scotland / Scottia, but also in Scandia / Scandinavia.
The Other World is for the Latvians vina willow, literally “the other sun”, the part of the world where the sun sleeps at night, as opposed to if willow “this Sun” which is the part of the world where men and where the sun is shining. The two form “the Universe under the Sun”… the Cosmos. It will be noted that this root vina is found in Vinéta, the Ys of the Germans, in the Vin-land of the Vikings and, no doubt also, in Vanes and Vénètes; as well as the root saul “soil, Sul, the sun”, but also Saüle “pillar”.

Source: http://lieuxsacres.canalblog.com