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I'm currently reading 'No Fixed address' by John Bodycomb. He had a interesting paragraph in relation to Hellonisation::
".... One of the mystery religions was Mithraism, after the Persian hero-divinity Mithras. Mithras was mediator between the unapproachable and unknowable divinity who reigned in remoteness, and the human race who were struggling and suffering here below. The story had it that after joining his disciples in a last supper, Mithras ascended to heaven..."I must say this has a familiar ring to it. It also gives some support to the idea that we are as humans able to add legend and myth to a story.
I've done a bit of a quick wikipedia search and could find Mithras but nothing about his ascension and 'last supper'. Never the less something to look into further.