To Philip K. Dick schizophrenia was a divergence of idios kosmos from koinos kosmos within the perception system of an individual. This divergence, induced by dehumanizing institutions and isolation, causes a feedback loop in which the schizophrenic is further isolated due to his inability to communicate the radically different idios kosmos that he percieves, thus exacerbates his schizophrenia, ad infinitum.

LSD and other entheogens gave PKD the insight that the extremely idiosyncratic idios kosmos of the schizophrenic might be closer to reality than the idios kosmos of the well-adjusted individual. The reality being a universe without the mediation of time and without percieved causality. The schizophrenic "gets it all at once". This experience is difficult to cope with and even understand.

This "overperception" and the consequential breakdown of the naming process that is key to uderstanding is what makes it difficult if not impossible to communicate the schizophrenic's idios kosmos to others:

"No-name entities or aspects begin to appear, and since the person does not know what they are -- that is, what they're called or what they mean -- he cannot communicate with other persons about them"
--"Drugs, Hallucinations, and the Quest for Reality" (1964)