Principle of Undifferentiated Encoding

the brain does not perceive light, sound, heat, touch, taste or smell. It receives only neuronal impulses from sensory organs. Thus the brain does not "see light," "hear sounds," etc.; it can perceive only "this much stimulation at this point on my body." The practical consequence is that all perceptions, let alone "thoughts," are deductions from sensory stimuli. They cannot be otherwise. All observations are therefore partly the function of the observer. This situation renders complete objectivity impossible in principle. (Heinz Von Foerster, "On Constructing a Reality.")