One may interpret his manic delusional outpouring as nonsense, to be ignored and discarded, or on the contrary receive it as valuable evidence of how mind functions and what mind is.

With my writing, specifically with my answering your letters, I am taking myself the advice which I have given and will continue to give, namely to write down, to write out, to reflect on, and perhaps even to expand, the thoughts that perplex and trouble us.  My advice to him to record his imaginings (Vorstellungen), his compulsive expressions of anxiety and fear by composing a novel differs only superficially from my need to explore my thoughts by writing them down. 

Notwithstanding the etymology, I consider it an error to presume fiction to be inherently untruthful, while "scientific" non-fictitious prose is deemed to state what is "true". I consider "fiction" to be a template, a framework, for individual thought and feeling which makes it possible to demonstrate truths that cannot otherwise be expressed. I consider "science" to be a template, a framework, for social thought and feeling which are in effect creative of a social nexus and that establish and confirms truths which are correspondingly more disseminated and effective.

If his delusions are neither constructive nor edifying, there arises the pressing question whether one should encourage him to express them or to deny them. Would such expression, as in a novel, be purgative or confirmative?  Arguably, the representation of the delusions would serve only to confirm them. That therefore they should be suppressed and their expression should be prohibited.  But to the contrary, there is the long tradition of tragedy and an experience which effects the purgation of pity and fear and the prophylactic and therapeutic effect of gazing on the brazen serpent.  I have given this issue much thought, and I conclude his delusions to be windows into the nature of the mind, of thought and of language.