I read a lot about John and things he wrote. He has always heard voices and seen spirits who apparently dictate him the music he writes. That was even before rehab and the descent into hell that was almost killing him.
There are at this point two explanations:
1. He is schizophrenic
2. He has "antennae" that "tap" into the music sphere that is there in the ether. I have other examples of the existence of this sphere. Paul McCartney has repeatedly said that he dreamed the melody of Yesterday and he spent the next week asking to all and sundry if they heard it somewhere. Keith Richard, Peter Gabriel and several other musicians have said that they heard the music already in their head, it was there.
My father is a conductor, arranger and composer. Once I asked him about the creative process and he said "I don't know, I just hear a melody in my head and I write it down".
