Consciousness as a phenomenon of life is something we think we are quite familiar with: It is the intrinsic sophisticated process that we let go of every night when we go to sleep and that returns to us every morning when we awake. Yet along with this state of awareness while being awake, other, deeper levels of consciousness exist that hold very different, peculiar properties: In the dream state for example, we perceive inner pictures as if they were outer events – sometimes accompanied by strong emotions, and all of this happens in a quite intense manner. Very often, in the moments of perceiving these pictures in the dream state, we are even unable to differentiate them from our outward, “ real ” experiences.
In terms of neurobiology, consciousness is simply regarded as a process that arises when millions of nerve cells in the brain and in the body communicate with one another on a physical-chemical basis. However, when it comes to what is called “subjective experience ” , we face a major problem, actually a problem that the above-described scientific explanation cannot provide a solution for: How can it be possible that nerve cells – even in a correlation of millions of cells – create or have what we call imagination? How can it be possible that nerve cells – even in a correlation of millions of nerve cells – think a thought? How can nerve cells have an experience of something, of anything? The subjective experience of “I have a feeling” cannot be displayed in neurobiological means and ways.
And also the art of philosophy – being in charge of explaining the human mind since ancient times – up to this day is not in a position to offer a satisfactory comprehensive elucidation of our mental and psychic states of being, or the world of the so-called qualia, i.e. the pixels of subjective feelings and awareness. We can definitely state as true: We as humans do perceive something, and we can definitely state as true that in doing so we make use of our nervous system. But is our physical nervous system the source of our subjective experience?
The World Knot or the mind-body problem
When I turn my gaze skyward I see the flattened dome of the sky and the sun’s brilliant disc and a hundred other visible things underneath it. What are the steps which bring this about? A pencil of light from the sun enters the eye and is focused there on the retina. It gives rise to a change, which in turn travels to the nerve layer at the top of the brain. The whole chain of these events, from the sun to the top of my brain, is physical. Each step is an electrical reaction. But now there succeeds a change wholly unlike any that led up to it, and wholly inexplicable by us. A visual scene presents itself to the mind: I see the dome of the sky and the sun in it, and a hundred other visual things beside. In fact, I perceive a picture of the world around me.
The scientific content of this statement made in the year 1940 by the great neurophysiologist Charles Sherrington is still valid today. Similar considerations may be made regarding the field of philosophy:
We suppose that a physical process starts from a visible object, travels to the eye, there changes into another physical process, causes yet another physical process in the optic nerve, and finally produces some effects in the brain, simultaneously with which we see the object from which the process started, the seeing being something “mental”, totally different in character from the physical processes, which precede and accompany it. This view is so queer that metaphysicians have invented all sorts of theories designed to substitute something less incredible.
For the time being and perfectly in line with the findings of modern science we therefore may give ourselves the permission of assuming the existence of unknown realms of reality without immediate violation of the physical laws of cause and effect known to us. Perhaps there really do exist other levels of reality that go far beyond the structures of scientifically provable truth.
 The term “world knot“ was first used by Arthur Schopenhauer (1788-1860). In finding this term, the German philosopher very accurately related to the point of linkage between subjective, i.e. inner experience and objectively describable outer events.
 Charles Sherrington, Man on His Nature, 2nd ed. (Cambridge, England: Cambridge University Press, 1951).
 Bertrand Russell, quoted in Sir J. Jeans, Physics and Philosophy (Cambridge, England: Cambridge University Press, 1943)