West, Indo-European Poetry and Myth (the *Dyḗus reconstruction)
The standard synthesis of comparative Indo-European poetics and mythology by a leading classical philologist. Chapter 4 assembles the case that PIE speakers worshipped Dyḗus (ph₂tḗr), "(Father) Sky": the cognate theonyms (Vedic Dyáuṣ, Greek Zeús, Latin Iū-piter/Diēspiter, Umbrian Iupater, Anatolian šīu-/Tiwaz-type reflexes, Germanic Tīwaz → Norse Týr, Baltic Dievas), the matching "father" epithet in three branches, and the shared semantic field (bright daytime sky; "day" words from the same root). This is the vault's clean descent benchmark: the methodology other motifs are measured against.
The formula equation Dyáuṣ pitṛ́ = Zeû páter = Iūpiter (with Umbrian Iupater) shows regular sound correspondence in both the noun and the kinship epithet — inheritance of a fixed phrase, not just a name (West 2007, ch. 4).
Regularity is the discriminator: each branch's reflex obeys that branch's own sound laws (*dy- → Skt dy-, Gk z-, Lat j-, Gmc t-), which borrowing after separation would not produce.
West's cautions: Anatolian šīu- means "god" generically (the figure, not just the root, must be argued); Germanic Týr reflects deywós "god/celestial one" rather than dyḗus directly; the sky-father's prominence varies wildly across daughters (Zeus central; Dyaus residual) — the name is inherited, the cult standing is not.
Class 3 by definition: no PIE text exists. The reconstruction is as strong as comparative linguistics gets — multiple branches, regular correspondences, matched formula — but reconstructed theology (what PIE speakers believed about Dyḗus) is far softer than the reconstructed lexeme*. West is occasionally criticized for over-collecting parallels; ch. 4's core is consensus material also found in Mallory & Adams.
sky-father