That's a naturalistic account. It is simultaneously cynical, patronising and inadequate (not on your part but as a cultural perspective). I think it's more that the ancients, or rather, pre-moderns, did not have a sense of themselves as being separated from or apart from nature in the way that we do. And that sense of separateness in turn comes from viewing humans from an objective perspective. — Wayfarer
Not sure if you're going to read all of this, but some more detail to discuss. These historical blurbs aren't entirely adequate, but maybe you can help me figure some more stuff out.
I probably generalized so much in my previous post that it came across as naive about the undoubtedly intricate nature of real causality. I would certainly say I've never put together based on my readings an exact timeline of human psychical/cultural development, if that's even possible. Some cultures are probably more prone to viewing the environment as spiritual, and some less, along with individuals. Looking at the topic from a perspective internal to rationale rather than in terms of cognitive structure with its reliance on physicalist modular notions, this is the basic idea I have at my current stage of comprehension:
The mystery of animateness in humans and animals has perennially fascinated Homo sapiens, and since it is not at all clear where the line should be drawn between inanimate mechanism and intention, especially in pre-scientific worldviews, we have tended to attribute soul to nature in general. Prehistorically, humans had a runaway instinct to interpret unexplained motion, in spontaneous phenomena such as the sunrise and the weather, as instigated by invisible spirits, with the perception of voices and apparitions in nature reinforcing this inclination. We see and hear the signs of vitality in ourselves and the creatures in relation to which this ability to predict and anticipate intention proves fruitful to our existence - the avoidance of the territorial haunts of dangerous predators, for hunting, etc. - and our psyches presumed intention in the atmosphere, water and all motivity. The cosmos seems intuitively to be an expression of spirit rather than a mechanistic system of interrelated variables in the absence of ubiquitous technologies fashioned from natural resources and stimulating our reinterpretation of them as inanimate appendages of our own mentality. Without precisely demarcated concepts of self, psychology and matter, everything seems as alive as we are.
So I'd claim that the prehistoric mindset viewed spirit as universally infused into experience, with no conceptual distinction made between technical procedures and what moderns would call supernatural.
As for how this transitioned into philosophy, my basic conception:
The first philosophical analyses were of a type that can be called naive realism, originating at roughly the advent of ancient Greek written records. Artistic creativity, spirituality and beliefs about existence had been intertwined in one and the same sorts of cultural expression stretching all the way back to ancient prehistory, an organic outgrowth of inspired human nature during which libido was discharged, the experience of beauty realized, and a maturing sense of truth communicated in symbolic form.
As technology took a great leap forward at the adoption of Neolithic farming village lifestyles with their greater demand for finely crafted tools and wares, their specialized occupational division of labor, and intensified analysis of novel ideas and techniques to meet the need for detailed explanation and intellectual exchange, written forms of truth purveyance also became enriched and increasingly systematic within an initial aesthetic medium of poetic verse. The first philosophy was Greek poetry, which underwent a gradual transition from symbolic metaphor to materialistic theory as the meaning and nature of the cosmos morphed into the substance of the cosmos and then into its constituent elements.
To my knowledge, the first philosophies were extremely materialistic, but not derived from systematic observational methods like those of modern science. The first philosophers such as Thales performed thought experiments with concepts like the four elements. Cultures beyond ancient Greece such as China had similar concepts, maybe altogether classifiable as a proto-atomism. As thinkers attempted to progressively generalize to essences, the literature became more metaphysical, the "One" of Parmenides, "logos", Mesopotamian sorcery-based philosophies, introspective Buddhist concepts of universal consciousness, etc. I think Plato's thinking involves a proto-psychological form/matter dualism, with ideas being instantiated forms. Aristotle expanded on Plato's theories by trying to analyze exactly how forms such as ideas relate to matter, arriving at the paradigm of hylomorphism.
Concepts of soul like neo-Platonic emanation theory existed throughout antiquity and the Middle Ages. It was the reintroduction of Aristotle's naturalism to Medieval Europe and then the movement of Ockamist nominalism that produced the modern paradigm of theoretically modeling nature, which was one of the motivations for invention of observation-enhancing technologies such as the telescope and the microscope, along with the development of better mathematical techniques such as Newton's calculus and an analysis of uncertainty by the likes of Descartes and Hume.
The form/matter distinction probably became mind/body dualism as anatomy advanced and synthesized with progressing paradigms of matter as technologyesque mechanism, leaving concepts of soul, preserved as sacred, in the dust. Philosophers regarded humans as unique in having a rational faculty in addition to the appetitive and vegetative processes of organic life in general, and completely broke through the "inaccessible soul" barrier with the European Enlightenment concept of transcendent universal reason and its secularized support for universal morality. A lot of time was spent refining this concept of rationality, from the Early Modern period to the 19th century. Locke's ideas of the understanding and Kant's categories of reason are instances.
In 19th century Europe, the concept of unconscious will evolving within arational economic, biological and cultural contexts came into vogue. Freud's concept of libido was probably derived from this paradigm, and he introduced psychological science, analysis of the human mind as composed of arational modular processes instead of a transcending rational structure. The challenge of philosophy of mind and neuroscience has been to reconcile modularity of the psyche with the modularity of brain and body in an all-encompassing theory of consciousness.
So to summarize, I think at the beginning of civilization human concepts of truth were not at all irrational but somewhat unintegrated. We had the capacity for complex technological practice, but concepts and proto-expressions of natural principles, the philosophical applications of symbolical systems, were extremely metaphorical and imprecise, more artistic than technical, so that we had to force by sheer willpower a connection in individual minds between the symbolic features of essentializing thought and those of more ingrained technological thinking in a multi-generational cultural process that produced technical discourse with its historical dimension. I don't view the idea that modern truth and related thinking differ from the prehistoric variety as cynical or patronizing. These earlier humans had the capacity to think in modern ways, but lacked the cultural conditioning to mold their minds into so to speak "modernization". This seems to me the basic developmental stages in the incarnation of our so considered "objectively true" reality.
Spirit in technology and belief transitioned into systematic matter and transcendent soul conjoined by forms as ideas. Matter became mechanistic, ideation became systematic reason, reason was bracketed as a subsidiary of arational will, and psychology developed an arational anatomy of the mind that moderns are trying to harmonize with anatomy of the body and material mechanisms in general.
Much cognitive dissonance.