You’ve used “different aspects of the same thing” several times, but without exposition of what the same thing would be. Is it spatial/temporal relations? But then, of what are they aspects? — Mww
In saying that the physical brain and nonphysical mind are two aspects of the same "thing", what is my understanding of this "thing" ?
Mysterianism
As Colin McGinn said, consciousness is "a mystery that human intelligence will never unravel". Mysterianism is the philosophical position proposing that the hard problem of consciousness cannot be resolved by present human understanding, though may be comprehensible with future advances of science and technology. For example, our understanding of the deeper problems of reality may be no more than that of a horse being explained the allegories within Hemingway's
The Old Man and the Sea, an understanding beyond the innate mental abilities of the animal, no matter how detailed or patient any explanation would be.
IE, A true understanding of the "thing" is, and will always be, beyond my ability.
Imagining the unimaginable
If the "thing" is beyond my human capacity to understand, then why do I believe it exists in the first place. We understand in the same way that language allows us the discuss other unimaginable things, such as time, space, causation, ghosts, gods, unicorns, the big bang, infinity, etc. However, this is not the language of the early Wittgenstein being a logical correspondence between language and the world, but rather language as metaphor. As Nietzsche wrote “We believe that when we speak of trees, colours, snows, and flowers, we have knowledge of the things themselves, and yet we possess only metaphors of things which in no way correspond to the original entities.”
IE, we can imagine the unimaginable through language, but not literally, only metaphorically.
Physicalism and nonphysicalism as two aspects of the same thing
There are many examples where one concept can be expressed as a combination of physical and nonphysical experiences. For example, i) aesthetics - needing both a physical form and nonphysical content, where, as Kant said, judgments of beauty are sensory, emotional and intellectual all at once.
ii) emotions - as Antonio Damasio, neurologist said "an organism can possess feelings only when it can create a representation of the body's functions and the related changes that occur in the brain"
iii) mathematics - both discovered and invented, and in the words of Mario Livio, "Indeed, I posit that humans invent the mathematical concepts—numbers, shapes, sets, lines, and so on—by abstracting them from the world around them. They then go on to discover the complex connections among the concepts that they had invented; these are the so-called theorems of mathematics" - iv) being - as expressed in the hylomorphism of Aristotle, where being is a compound of matter and form, necessitating both the physical and the nonphysical, v) language - the later Wittgenstein writing in Philosophical Investigations that the meaning of a word is its use in language, where meaning occurs in a nonphyiscal mind and use occurs in a physical world.
IE, there are many examples where the physical and nonphysical have something in common.
Panqualityism
My feeling is that panqualityism, a view promoted by Sam Coleman, is the most reasonable theory to explain the connection between the physical brain and the nonphysical mind. Panqualityism can be seen as a kind of middle way between panpsychism and physicalism. Whereas the physicalist thinks that we can give an entirely reductive account of consciousness, the panpsychist thinks that consciousness is fundamental, and the panqualityist thinks that that the qualitative aspect of consciousness is fundamental, whilst holding a reductive view of subjectivity.
It is argued that sentience on Earth developed as early as the Cambrian period with the Cephalopods 541 to 485 million years ago. It seems reasonable to assume that consciousness is a property of sentience, and is a function of the complexity of the particular sentient being. There is a choice of belief, either i) there was a day when consciousness didn't exist and the next day it did, or ii) consciousness has always existed though to a lesser degree. Both possibilities are mysterious, though I find possibility ii) the more reasonable. Going further back in time there is another choice, either i) panpsychism, where atoms are conscious or ii) panqualityism, where atoms are not conscious but in certain combinations are able to give rise to consciousness. Again, both possibilities are mysterious, though I find possibility ii) the more reasonable.
IE, given the choice of many mysteries, I find the idea of panqualityism the least mysterious
Conclusion
In summary, the "thing" that has the two aspects of physical brain and nonphysical mind
may best be understood by the theory of panqualityism. However, this can only ever be a metaphorical understanding rather than a literal understanding.