"I am the wisest man alive, for I know one thing, and that is that I know nothing. " --- Socrates
Observation can be considered as the first step of our understanding reality. We may trust our observation without thinking twice because we believe that what we see cannot be false. However, I found otherwise: our observation often is subjective, even far from true. This is because that so often we look at things with biased eyes. In other words, our observation is often controlled by our THOUGHTS, we see only what we want to see, or we unconsciously ignored those evidences that would disprove our thoughts.
Making example of art learning. During perspective practice, many people without previous training would draw the bottom of a cylinder as a straight line (or a curve that is not curved enough), even though what they see is actually a curve (the degree of the curve is depend on angles). Why? I found the answer is rather simply, because they THINK the bottom is flat. This fact demonstrates perfectly how we use our THOUGHTS control our observation: we think the bottom of cylinder is flat, so we should draw a straight line, regardless what we actually see is a curse. (see image on the right)
Another example is how we humans treat homosexuality. Until today, among most people in the world homosexuals are abnormal, which mean it is contradictory to our understanding of human nature, which is: we humans are all born heterosexual. Do we really understand human nature that well? Truth is, homosexuality has been existing along with human being. Scientists even found that homosexual behavior also exists in animal world. These facts are enough to prove that homosexuality is something natural. And what really is "unnatural" or "abnormal" is our thought, or understanding about human nature.
Not only "ordinary" people are often falling such observation - thoughts distortion, but also some geniuses would do the same. Einstein, the person who challenged Newton when he was only 25, refused to accept Quantum theory, a new field of study that Einstein himself helped to establish. The reason Einstein rejected this theory was because it was so obviously contradicts classical physics, also to "common sense". But both theoretical and experimental studies showed that Quantum theory was "neither wrong or incomplete" (Einstein Decoding Universe, Francoise Balibar, Discoveries, 2001). So despite Einstein's rejection, quantum theory had been developed quickly and contributed tremendously to modern technology.
My mentioning this part of Einstein does not mean to say that Einstein was not a genius, only to say that even a genius would have his/her "human limitation" (I know nothing about physics but I would still keep an open mind, that one day, maybe Einstein's doubt on quantum theory would be proven to be right). I also think, that this example also demonstrates that our human reasoning has its limitation: something doesn't fit our common sense, or logical reasoning, doesn't necessarily mean it is not true.
There are many more examples in real life on this "subjective observation". We often hear people saying "I don't get this" or "I can't get that", this usually just means that what we see don't fit our existing understanding. Our "theorems" are highly limited, variation in real life is infinite, using limited "theorems" to measure infinite variation, of course we will often be in dead ends. Had we changed our bad "hobby", look at things not from "thoughts", but from reality itself, things would be much easier for us to understand.
Why we humans are so obsessed with out theories, or thoughts? This surely involves some complicated scientific study about how the "consciousness" evolved, and is certainly beyond my knowledge and capability (or we can simply blame "snake" of Eden, who brought us the "fruit of wisdom"). But what I am more and more convinced is, that we human since obtained consciousness, developed an obsession with it, feeling an extreme satisfaction when exaggerating its potential, and eventually became some sort of "bigotry". Our tradition, ideology, moral standards, all are just some "temporary logic" ("temporary" here can be "decades", "hundred", or more than "thousands" years), but they have been taken by many people, generation to generation, as "absolute", and used as standards to judge reality. In fact, I think it is exactly these "absolutes" that mostly need to be re-thought or re-examined.
If we look back history, it is not hard to realize that almost every step forward we made, was based on overthrowing some existing "absolute": heliocentric took over geocentric theory, evolution challenged divine creation, relative space-time refuted absolute space and time, democracy replace despotism, etc. So I think the most important "rule" we may follow is, whenever we hit the "dead end", instead of throwing judgments, we rethink our thoughts or beliefs. Only if we can doubt our belief, dare to overthrow the premise of our "logic", admit the limitation of human intelligence, we can be credited as "open minded". On the other hand, only if we take our thoughts as relative, as possible faults, we can have acute observation, be able to see some relative truth.
Of course, essentially speaking, our visions are all limited. That's why I believe that human wisdom is measured not by how much we know, but by how much we acknowledge the limitation of our intelligence.