I was just reading about the terrifying effects of datura, and thinking the very same thing - man is not meant to know some things. In AC Clarke's "Childhood's End", at one point a Ouija board is produced. The Overlords are fascinated by Earth's occult behaviors - for reasons men don't get. In any case the Ouija board spells out

REMEMBERMANISNOTALONENEXTTOMANISCOUNTRYOFOTHERS

I get goose bumps as I write that - the greatest single moment in science fiction. Man is becoming not-Man, and there won't be any resemblence.

Thanks for the synopsis, I suppose I will read it after all. I've got an IWETHEYer expert a few miles distant.