Dyēus
While its existence is not directly attested by archaeological or written materials, "*Dyēus" is considered by scholars the most securely reconstructed deity of the Indo-European pantheon, as identical formulas referring to him can be found among the subsequent Indo-European languages and myths of the Vedic Indo-Aryans, Latins, Greeks, Phrygians, Messapians, Thracians, Illyrians, Albanians and Hittites. Name. Etymology. The divine name "*Dyēus" stems from the root "*dyeu-," denoting the "diurnal sky" or the "brightness of the day" (in contrast to the darkness of the night), ultimately deriving from *"di" or "dei"- ("to shine, be bright"). Cognates in  Indo-European languages revolving around the concepts of "day", "sky" and "deity" and sharing the root "*dyeu"- as an etymon suggest that Dyēus was the vast and bright sky of the day conceived as a divine entity, such as Sanskrit "dyumán-" 'heavenly, shining, radiant'. A vṛddhi-derivative appears in *"deywós" ("celestial"), the common word for "god" in Proto-Indo-European. In classic Indo-European, associated with the late Khvalynsk culture (3900–3500), "*Dyēus" also had the meaning of "Heaven", whereas it denoted "god" in general (or the Sun-god in particular) in the Anatolian tradition. The suffix-derivative "*diwyós" ("divine") is  also attested in Latin, Greek and Sanskrit. The noun ("day"), interpreted as a back-formation of *"deywós", has descendant cognates in Vedic Sanskrit "divé-dive" ("day by day"), Latin "Dies", goddess of the day and counterpart to Greek Hemera, Hittite "siwat" ("day"), Palaic "Tīyat-" ("Sun, day"), Ancient Greek "endios" ("midday"), Old Armenian "tiw" (տիւ, "bright day"), Old Irish ("nine-day period"), Welsh ("today"), or Slavic "Poludnitsa" ("Lady Midday"). While the Greek goddess Pandeia or Pandia (, "all brightness") may have been another name for the Moon Goddess Selene, her name still preserves the root "*di"-/"*dei"-, meaning "to shine, be bright". Epithets . The most constant epithet associated with *"Dyēus" is "father" ("*phtḗr"). The term "Father Dyēus" was inherited in the Vedic "Dyáuṣ Pitṛ́", Greek "Zeus Patēr", Illyrian "Dei-pátrous", Roman "Jupiter" (*), even in the form of "dad" or "papa" in the Scythian "Papaios" for Zeus"," or the Palaic expression "Tiyaz" "papaz". The epithet "*Phtḗr Ǵenh-tōr" ("Father Procreator") is also attested in the Vedic, Iranian, Greek, and perhaps the Roman ritual traditions. Role. "*Dyēus" was the Sky or Day conceived as a divine entity, and thus the dwelling of the gods, the Heaven. As the gateway to the deities and the father  of both the Divine Twins and the goddess of the Dawn ("*Héwsōs"), "*Dyēus" was a prominent deity in the Proto-Indo-European pantheon. He was however likely not their ruler or the holder of the supreme power like Zeus and Jupiter. "*Dyēus" was associated with the bright and vast sky, but also to the cloudy weather in the Vedic and Greek formulas "*Dyēus' rain." Although several reflexes of Dyēus are storm deities, such as Zeus and Jupiter, this is thought to be a late development exclusive to Mediterranean traditions, probably derived from syncretism with Canaanite deities and the Proto-Indo -European god "*Perkunos". Due to his celestial nature, "*Dyēus" is often described as "all-seeing" or "with wide vision" in Indo-European myths. It is unlikely however that he was in charge of the supervision of justice and righteousness, as it was the case for Zeus or the Indo-Iranian Mithra–Varuna duo; but he was suited to serve at least as a witness to oaths and treaties. Proto-Indo-Europeans also visualized the sun as the "lamp of Dyēus" or the "eye of Dyēus", as seen in various reflexes: "the god's lamp" in Euripides' "Medes", "heaven's candle  in Beowulf", "the land of Hatti's torch" (the Sun-goddess of Arinna) in a Hittite prayer, Helios as the eye of Zeus, Hvare-khshaeta as the eye of Ahura Mazda, and the sun as "God's eye" in Romanian folklore. Consort. "*Dyēus" is often paired with "*Déǵōm", the Earth goddess, and described as uniting with her to ensure the growth and sustenance of terrestrial life; the earth becomes pregnant as the rain falls from the sky. The relationship between Father Sky (*"Dyēus Phtḗr") and Mother Earth ("*Déǵōm Méhtēr") is also of contrast: the latter is portrayed as the vast  and dark dwelling of mortals, located below the bright seat of the gods. According to Jackson however, as the thunder-god is frequently associated with the fructifying rains, she may be a more fitting partner of "*Perkunos" than of "*Dyēus". While Hausos and the Divine Twins are generally considered the offsprings of "*Dyēus" alone, some scholars have proposed a spouse-goddess reconstructed as "*Diwōnā" or "*Diuōneh", with a possible descendant in Zeus's consort Dione. A thematic echo occurs in the Vedic tradition as Indra's wife Indrānī displays a similar jealous and quarrelsome disposition under provocation. A second descendant  may be found in Dia, a mortal said to unite with Zeus in a Greek myth. The story leads ultimately to the birth of the Centaurs after the mating of Dia's husband Ixion with the phantom of Hera, the spouse of Zeus. Another reflex may be found in the Mycenaean Greek "Diwia", possibly a feminine counterpart of Zeus attested in the second part of the 2nd millennium BC and which may have survived in the Pamphylian dialect of Asia Minor. The reconstruction is however only based upon the Greek—and to a lesser extent the Vedic—tradition, and it  remains therefore not secured. If the female goddesses Hera, Juno, Frigg and Shakti share a common association with marriage and fertility, Mallory and Adams note however that "these functions are much too generic to support the supposition of a distinct PIE 'consort goddess' and many of the 'consorts' probably represent assimilations of earlier goddesses who may have had nothing to do with marriage." Evidence. Cognates stemming either from the root "*dyeu" ("daylight, bright sky"), the epithet "*Dyēus Phter" ("Father Sky"), the vṛddhi-derivative "*deiwós" ("celestial", a "god"), the derivative "*diwyós" ("divine"), or the back-formation (a "day") are among the  most widely attested in Indo-European languages. Sky-Father epithet. Ritual and formulaic expressions stemming from the form *"Dyēus Phter" ("Father Dyēus") were inherited in the following liturgic and poetic traditions: Other reflexes are variants that have retained both descendants of the root "*dyeu-" ("sky") and the original structure "Father God". Some traditions have replaced the epithet "*phter" with the nursery word "papa" ("dad, daddy"): Other variants are less secured: Section::::"Celestial" derivations. Cognates stemming from *"deywós", a vṛddhi-derivation of *"dyēus" (the sky-god) are attested in the following traditions: Other cognates are less secured: Other cognates deriving from the  word "*diwyós" ("*dyeu" "sky" + "yós", a thematic suffix) are attested in the following traditions: Legacy. As the pantheons of the individual mythologies related to Proto-Indo-European religion evolved, attributes of "*Dyēus" seem to have been redistributed to other deities. In Greek and Roman mythology, "*Dyēus" was the chief god, while the etymological continuant of Dyēus became a very abstract god in Vedic mythology, and his original prominence over other gods largely diluted. In Slavic tradition. At one point, early Slavs, like some Iranian peoples after the Zoroastrian religious reformation, demonized the Slavic successor of "*Dyēus" (abandoning this word  in the sense of "heaven" at the same time, keeping the word for "day", however, and abandoning many of the names of the other Proto-Indo-European gods, replacing them with new Slavic or Iranian names), while not replacing it with any other specific god, as a result of cultural contacts with Iranian peoples in the first millennium BC. Hence, after the process of demonization by the Slavs, "*Dyēus" is considered to have originated two continuations: "*divo" ("strange, odd thing") and "*divъ" ("demon"). The result of this demonization may be Pan-Slavic demons, e.g. Polish and Czech dziwożona, or Div  occurring in "The Tale of Igor's Campaign". According to some researchers, at least some of "*Dyēus"'s traits could have been taken over by Svarog (Urbańczyk: Sun-Dažbóg – heavenly fire, Svarožič – earthly fire, Svarog – heaven, lightning). Helmold recalls that the Slavs were also supposed to believe in a god in heaven, who only deals with heavenly matters and commands other gods. In non-Indo-European traditions. Various loanwords of *"deiwós" were introduced in non-Indo-European languages, such as Estonian "taevas or" Finnish "taivas" ("sky"), borrowed from Proto-Indo-Iranian.