I very much doubt that Aristotle would agree with your notion that some things are necessarily hidden, since the presence of the occult would make philosophy pointless, as all inquiry would end with hidden causes. Anyway it’s a good job that neuroscientists, including Catholic neuroscientists, don’t believe in the occult, or at the slightest difficulty they’d say “there you go, told you, it’s forever hidden, anyone for golf?”.
If we are speaking Aristotle/Aquinas we need to properly understand what is meant by “occult”.
These days it has New Age, Spiritualist implications which is not at all what the above philosophers mean.
Even the word “hidden” is ambiguous.
Take the accelerated movement of the celestial bodies (ie allegedly circular motion).
Now Aquinas is surely correct that whatever is moved (ie accelerating) must be moved (ie persistently acted upon) by another. (OK he prob didn’t mean it quite this way but I am interpretting him in the best light consistent with Newtyonian physics).
Therefore Aristotle/Aquinas had a problem … where in the sky is the cause…what material thing is causing this effect? Ultimately there isn’t a material one to be found.
Consequently logic suggests, if the above principle is true, that there must be a cause that is immaterial. In other words, there is a realm of “being” that is non-material…yet is capable of “animating” matter - whether it be a brain, a planet or a star.
I find that a perfectly acceptable form of logic and philosophic conclusion.
It isn’t necessarily “occult” (though it could easily lend itself to that sort of New Age spin).
Of course, in the above example, Aristotle was wrong.
The cause was of course “not material”, but different from how he thought of it (“Uncaused Cause”) … it was the invisible force of gravitational attraction…which ultimately is caused by the mass of all other material bodies in space.
Are such forces “material” or “non-material”. While its an interesting question I think its a tangent. They are but instrumental agents in the movement of the celestial bodies. The originating efficient cause is really just other celestial bodies which clearly are material.
But back to brains.
Can the activities brains exhibit (“effects”) be explained adequately by chains of material causality…or must we posit the existence of something we cannot observe/sense as the primary cause? If we do then this is all we mean by “occult” or “hidden” or “spiritual”.
Hence the soul stuff.
And if we do have to go this way there is a further decision to be made.
Is this “soul” standalone (ie can exist even apart from the matter it effects) or is the soul and the organised matter it “effects” so intertwined that it is illogical to speak of one without the other?
This is where classic Aristotle and Aquinas seem to part company. Classic Aristotle had no time for a soul that persists when a man dies. Aquinas clearly does under the Christian imperative.
Confusingly, “Christian” philosophers of Aristotle hold that Aristotle did imply the eternity of the human soul. It appears Aristotle was ambiguous on this point in his writings…at least according to christians.