I can't remember anything specific from my own memory at this point, but perhaps similar to the direction you are going is the issue of dreams:

Knowledge of the Gods as "Manifest"
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That is a fascinating line of thought, Nate .
My thoughts have most consistently turned to thinking of the prolepsis of the gods as connected with the capacity of all humans (I would think) to experience awe and wonder, but I can't readily point to an academic paper or ancient text to back me up on that.
Mind-altering substances and rituals we're definitely part of ancient cultures. Lookin' at you, Dionysus!!
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Long & Sedley On Gods (attached)