Jaynes proposes that in the Iliad the Greeks "heard the voices of the gods" and used those to make decisions. In our modern society I'm sure a lot of religious people would find God(s) speaking directly to them a fabrication of the mind, but auditory hallucinations are common and well documented. I often find on the edge of sleep I can lucidly think of a tune or song and hear at as clearly as if it was actually being played in the room.

I think Jaynes made a really interesting observation about older theistic societies that took for granted the ability for people to receive instructions in their heads from the gods. It seems commonplace in religious literature at the least that people can interact with gods and hear what they have to say, something which we tend to interpret more as a metaphor nowadays.

If we reject his theory on consciousness as being a modern substitute for heavenly direction, I don't think that necessarily rules out a cognitive function that we've lost over the past few thousand years - one which could have developed from a young age by not writing off auditory hallucinations as mental noise...