Eyes are our most important sense organs because we usually only believe something when we actually see it with our own eyes.
The Greek philosopher Plato explained why we should not always trust our eyes. He was right, of course, because our eyes cheat us more often than we think.
Seeing is Believing
Nowadays, if we wish to understand how the process of vision actually works, we have to look not only at the explanations supplied by the laws of physics, but also at cognitive science. On a purely objective basis, the knowledge acquired by this science has justified the skepticism which philosophers have had for thousands of years concerning the question as to whether an objective reality is accessible to mankind. Is what we see reality or is it "only" the fabrication of our brain? The latter has now been shown to be true. For vision, this means: we cannot objectively see the real world.
This can be clarified by some of the discoveries which have been made in the field of cognitive science: the information forwarded to the brain by the receptors in the eye is neutral from the viewpoint of meaning. It is not until it actually reaches the brain that these signals are given meaning and sense on the basis of previous experience. Therefore, what people see and perceive is their own personal construction of reality. In the words of a renowned cognitive scientist, Gerhard Roth, this means:
"The brain sees, hears, smells and feels nothing about the world."
Why? The brain can only understand physico-chemical signals. These signals, and only these signals, can switch the interconnected nerve cells to a physiological state of excitation. Light quanta, sound waves or smell molecules - the information received by our sensory organs - are all unable to do this. In the words of the cyberneticist Heinz von Foerster: "The environment we perceive is our invention."
Well-known examples illustrating the way in which our brain works are found in Gestalt psychology in the form of Kanizsa and Kipp figures. |  Example 1
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