Here is a loosely-related question. First, Leibniz, on the difficulty of reducing mental phenomena to physical ones:
"Moreover, it must be confessed that perception and that which depends upon it are inexplicable on mechanical grounds, that is to say, by means of figures and motions. And supposing there were a machine, so constructed as to think, feel, and have perception, it might be conceived as increased in size, while keeping the same proportions, so that one might go into it as into a mill. That being so, we should, on examining its interior, find only parts which work one upon another, and never anything by which to explain a perception."
It is in the original Latin. Hurray you picked up Latin!
People discriminate between spirit and matter on the grounds that spirit is intentional (has "aboutness"), qualitative (has "what-it's-likeness") transcendentally united, without extension, transparent, diaphonous, doop de doop. But if you focus on how the spiritual process of the brain differs from the physical processes of the brain then the stand-out feature is seriality. Almost everything that happens in the brain is massively parallel. So could you -- & I think this one might just be a stupid question -- look on spirit as an evolutionary solution to seriality, rather than seriality as a necessary aspect of spirit? What adaptive advantages could a serial mechanism confer on a brain?
(Dennett's Multiple Drafts model, illustrated by the Phi phenomenon, complicates that seriality somewhat. There is no "leading edge" of consciousness in this story; one continuity is confabulated from many temp continuities; the mind slips through timespace like a snake through grass, its tail turning depending on where it wants to poke).