Concept
reconstructed · c. 4500–2500 BCE
Proto-Indo-European (PIE) is the reconstructed common ancestor of the Indo-European languages — the vast family that includes Greek and Latin, Sanskrit and Persian, the Celtic, Germanic, Slavic, and Baltic tongues, Armenian and Albanian, and the long-dead Hittite and Tocharian. It was never written down, and is spoken by no one. Yet by the patient comparison of its many daughters, scholars have recovered a great deal of its sounds, its words, its grammar — and even, in outline, the gods and myths of those who spoke it.
It was probably spoken between roughly 4500 and 2500 BCE. The prevailing view sets its homeland on the Pontic–Caspian steppe north of the Black Sea, whence its speakers — herders of cattle and horses, masters of the wheel and the wagon — spread east and west in the long migrations that carried their descendants' speech, over millennia, from Ireland to India. (An older rival theory looked instead to Anatolia as the cradle.)
The kinship of these languages was famously announced in 1786 by Sir William Jones, who observed that Sanskrit bore to Greek and Latin an affinity 'stronger than could possibly have been produced by accident' — so strong that all three must have 'sprung from some common source, which, perhaps, no longer exists.' From that insight grew the science of comparative philology.
Its method is the comparison of cognates — words inherited from a single original, such as Latin pater, Greek patēr, Sanskrit pitṛ, and English father. By charting the regular correspondences of sound between such words — the so-called sound laws — linguists work backward to the lost forms behind them, marked always with an asterisk to show they are reconstructed, not attested: thus the PIE word for 'father' is written *ph₂tḗr.
For the tradition this library gathers, the deep interest of all this is that it reaches behind even Homer and Hesiod's Theogony to a far older stratum of belief. The very names and epithets of the Greek gods preserve Indo-European roots, and the comparison of Greek myth with the Vedic hymns of India, the lore of the Norse and the Celts, and the rites of early Rome lets scholars reconstruct, in outline, the religion of the common ancestors — a luminous, sky-bright pantheon headed by a Sky Father whose name survives, scarcely altered, as Zeus himself.
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