There's a story of a woman who had been blind since childhood. After she had radical surgery, she saw four brilliant shafts of light separated by dark valleys. Puzzled, she turned to a nurse, to be told that she was looking at her own fingers. There is evidence from early eye surgeries (when surgeons first learned to remove cataracts) that some patients who had their sight restored overnight were plunged into a mystery that overwhelmed them. They had no visual idea of form, size, or distance. Some even asked for the bandages to be replaced. When one was asked how big her mother was, she set her two index fingers a few inches apart. Some took months to tell the difference between a sheep and a tree. A comment of poet Gerard Manley Hopkins comes to mind: "When I look hard at something it seems to look hard at me as if my eye were still growing".When I ran across the above passage a few weeks ago, it brought to mind a salient fact of the human mind; to a certain extent, we are conditioned to view reality in a certain way. The mind is not simply a passive receptacle of what our eyes see and our ears hear; on the contrary, it actively constructs models of the external world, using those sense perceptions as building blocks. In many cases, the mind does this pre-consciously, and we are not even aware of it taking place. With respect to our sense of vision, those of us who have been sighted all our lives don't even give it any thought. In fact, the reality that our minds construct are so taken for granted that it never even occurs to us that reality might not be exactly as we perceive it to be.
-- Alan Jones, Reimagining Christianity (p. 205)
Some two decades ago, I read an article in the New York Review of Books about a certain kind of color blindness where individuals actually saw the world in black and white, unlike typical color blindness. I don't remember much about the article now (which may have been written by Oliver Sacks, although I'm not sure), except to recall that the research on this phenomenon demonstrated certain ways in which the brain actively constructs what we think of as "sight". I was unable to find any reference to the article via a quick internet search, but I did find this article from 1993, titled "The Vision Thing: Mainly in the Brain":
Vision, of course, is more than recording what meets the eye: it’s the ability to understand, almost instantaneously, what we see. And that happens in the brain. The brain, explains neurobiologist Semir Zeki of the University of London, has to actively construct or invent our visual world. Confronted with an overwhelming barrage of visual information, it must sort out relevant features and make snap judgments about what they mean. It has to guess at the true nature of reality by interpreting a series of clues written in visual shorthand; these clues help distinguish near from far, objects from background, motion in the outside world from motion created by the turn of the head. Assumptions are built into the clues--for example, that near things loom larger, or that lighting comes from above.It is often so ingrained in us that our perceptions of the universe are simply "the way it is" that we don't realize that these perceptions are the result of an active process of the human mind. Because we are used to the way we conceive of our perceptions, and because most of us actively engage the world with our minds in the same way, and because the way we conceptualize things works so well for us--we easily forget that what we see and hear is not simply the sum of what the senses gather from the world. The mind actually organizes and interprets what it receives from the senses.
Immanuel Kant made the point that the human mind has certain kinds of a priori means of synthesizing knowledge. The mind, he argued already "knows" a priori about certain concepts that we take for granted--space and time, for example.
When, as a teenager, I rejected the religion of my upbringing, I became a radical empiricist. I simplistically believed that all knowledge must necessarily come empirically, and since God could not be empirically verified, God must therefore not exist. This, to me, represented the height of rationalism. In reality, Empiricism, or perhaps logical positivism, had become my new faith; I had simply substituted one faith (religion) for another. But over time I came to realize that things are not quite so simple. There is a deeper reality that we can only pretend to understand. Some of the ways we build our understandings of the world--the a priori forms of knowledge like space and time that Immanual Kant pointed to--are so ingrained in the cognitive faculties of the human brain that we take them for granted. But other ways of perceiving reality are, no doubt, learned. Perhaps, as illustrated by the story of the blind person who, after surgery, did not recognize their own hands, we learn very early in our lives how to actively construct our models of reality.
Science is always trying to get at the deeper truths that lie behind the physical world. The deeper physics goes, the weirder it gets, and thus the more removed from our everyday reality it becomes. Quantum physics is very weird indeed. String theory, which is at present highly speculative, would, if proven to be true, show a reality that is even weirder.
The deepest realities of the world are beyond our understanding. God, which I consider the ultimate reality, is clearly the greatest, most elusive mystery of all. The great mystics of all religious traditions have always tried to penetrate beyond the superficial perceptions of reality, in order to come in contact with that which is the deepest and most profound. Mystics seek to throw off our traditional ways of understanding in order to accomplish this.
We all must live in the everyday world. I cannot pretend that my ways of perceiving the world are meaningless. If I see a car going down the street at a high rate of speed, knowing that the car's supposed solidness is an illusion, because it really consists of empty space filled by millions of quantum events, does not change the fact that it would feel very much like solid metal if it should come in contact with me. I choose therefore not to step out in front of a moving vehicle.
There are practical reasons why our minds construct models of the world as we do. We live at the the intersection between the deepest realities and the superficial world we think we perceive. The sacred mystery of God is about living in this world, not escaping from it. We are contained within God, and God within us. The big task for the religious soul is to figure out how to mystically join the deeper, mostly impenetrable reality of God with the mundane lives we must lead. The best I can make of this intersection between the mundane and the sublime is that we manifest its presence through the power of love.
If the doors of perception were cleansed every thing would appear to man as it is, infinite. For man has closed himself up, till he sees all things thro' narrow chinks of his cavern. -- William Blake