Matter and mind, symbol and meaning, object and subject, action and intention, determinism and free will, substance and form, concrete and abstract, actual and imaginary, fact and interpretation. All expressions of the same fundamental conundrum.
The brain is a material thing; the mind is an abstraction, a pattern, an interpretation of the brain's activity. No thought can flicker through the mind, unless a neuron fires in the brain. The mind has no independent reality; it exists like a reflection or a shadow. Realizing this, the mind despairs.
Wait! The mind is not so powerless. Here is a clue to the heart of this mystery: the immaterial mind is able directly to manipulate some physical matter just by thinking about it. I'm not talking about spoon-bending, I'm talking about the brain. Through conscious exercise of will, the mind constantly reshapes its physical substrate (and thereby reshapes itself). For example, the mind can choose to devote time and effort to learning a language, or a musical instrument, or a sport. It can devote itself to a spiritual path or a program of self-improvement. Each of these choices will have effects on the physical structure of the brain, stimulating activity and growth in some areas and suppressing it in others. Brain scans show this; and neuroscience is beginning to understand some of the correspondences.
There's nothing supernatural or spooky about the power of the mind to influence (some) matter directly. But I think it throws a bright light on a deep philosophical mystery. We minds imagine ourselves to be helpless epiphenomena of matter, while at the same time ceaselessly influencing the course of events.
Dwell on this: Where do my thoughts come from? Mind, or matter? What is the seed of intention? What is upstream of this river of thought? This question and all other truly deep questions are reflections of each other.