What I've noticed in the discussions here is that many people endemically haven't established for themselves whether the abstract mental even exists, as opposed to the physiological, material.
One e-book (free online) I read called "I changed my Mind [Ramonsky]"** explains the problem lots of people have dealing with abstractions, including an understanding of themselves as such, really well in terms of something called Matrix Theory. It explains how the natural growth of human neuro-systems provides the hardware for what is called M5-6 levels of abstract thought by the time one is in their late teens.
The problem is, as people like Wallace expound on beautifully in "Toward the First Revolution of the Mind Sciences"*, is that a lot of our education is "thing" oriented, like the western sciences; even the most used languages are noun centered (as a counter-example, Blackfoot Indians can converse in their language for days without using any nouns).
IMO, One of the less desirable results of this general "thing is king' orientation is that it can hinder these abstract layers from being acknowledged, honed, used. Immersion in popular material 'mysticism' can literally leave an adult working mentally in an adolescent Matrix Level. People who proclaim with absolute certainty that mind is just jelly-like meat in their heads are disciples of this adolescent mysticism.
I found another useful analogy in studying computer routers which describe computer functions in terms of layers: The physical layer, the data link layer..., the application and program layers, etc. each defines a different level of abstraction of these merely mechanical systems.
Critical thinking, art, invention, so-called "mythologies", humor, mathematics and metaphorical subtlety, even language and culture themselves are some of the byproducts from those who hone these levels of mental abstraction, who've matured regardless of the present popular tidal wave of materialistic fad.
Whether a fresh idea is considered a symptom of schizophrenic delusion or a profound metaphor depends on the maturity of mind addressing it.
From personal experience, I can only describe tangentially how important writers were in my own growth in terms of developing my powers of abstract thought, especially speculative authors like Heinlein, Clarke, Tiptree, Russell and Hogan. But lot's of other sources can accomplish the same kind of thing, like Lao Tzu, Alan Watts and Daniel Quinn.
~especially read pages 3-7