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The Druidic system collapsed when the Romans conquered Celtic lands and Christianity converted Celtic peoples. The Romans killed Druids systematically, viewing them as political threat. The Christians marginalized them, establishing written scripture as superior to oral tradition.
But the deepest blow came from disruption of the transmission chain. Druidic knowledge required unbroken lineage—master teaching student across decades. When a generation of Druids died without passing on their knowledge, it was lost irretrievably. No texts preserved it. No archives contained it. It existed only in memory, and when the memories died, so did the knowledge.
Some remnants survived in Bardic schools (which persisted in Ireland until the 17th century), in folk practices (which encoded fragments of old wisdom), in the written mythology (set down by Christian monks who preserved what they thought harmless).
But the full corpus of Druidic philosophy—the complete legal codes, the astronomical calculations, the medical formulas, the theological speculations—vanished. We know it existed (Roman accounts confirm this), but we cannot recover it. It died with the last Druids who could recite it.
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