I would love to see the other side of all of this correspondence. It would be fascinating to find out how (if at all) people responded to what Dick is trying to explain to them.

This appears to be a third letter to Malcolm Edwards. Dick references a January 30th letter that wasn’t included here. He expands on something he must have brought up in the second letter about some kind of structure that surrounds people and allows only them to receive a certain signal. These disinhibiting signals are created by the combination of several otherwise innocuous things like signage or advertising which trigger the neural firing of someone primed to receive it. The Creator is the one who programmed this whole signaling system in a deterministic way, and living creatures are the only things real in this universe. Everything else is just artificial props and scenery.

Dick takes a break from writing Claudia to send a letter to Malcolm Edwards at the beginning of 1975. Edwards reviewed Flow My Tears, The Policeman Said in the December ’74 issue of the British magazine Science Fiction Monthly. In that piece Edwards elucidated some things about the story that Dick had never been able to properly explain. 

Everyone has a private world (idios kosmos) which is contrasted by everyone’s shared reality (koinos kosmos). Dick wonders if a tyrannical state, for instance, could manipulate its citizens’ inner world through media and news to such an extent that they create a false universal reality. The world Dick wrote about in Ubik after everyone died was the true koinos kosmos that was revealed after everything else was stripped away, but he didn’t realize at the time that’s what he was getting at. 

He goes on to explain to Edwards how he transduced external electrical fields (I still don’t know what this means exactly) through his vitamin megadosing routine to improve his neural firing and cause the right hemisphere of his brain to ‘come on.’ Through this the true koinos kosmos emerged and he encountered the Immanent Mind.