“Suppose yourself looking through blue glass at a white horse. You would not believe it to be a blue horse, although it looks blue through the glass. You know that the blue glass gives an incorrect impression and therefore you are not deceived. Again, suppose you look into a curved mirror and see your much distorted reflection. Do you believe that is the true reflection? No, you know better, you know that the mirror distorts, and therefore you are not deceived. Suppose, however, that you had always looked through blue glass or into a mirror which distorts, and had been educated to believe what you saw to be correct. You would be in a position analogous to that of all mortals who are believing in sense testimony. You would have a conception of the universe very different from the normal. Yet you might go through life like any other person, gaining an education, doing your part in the world’s work, joining in all the activities of daily living, yet not knowing any vision but that which these misleading things gave you.
The only evidence we have of material existence is through the five physical senses, and from infancy we have been educated to believe them, no matter what they say. But are these sense reliable, do they always tell you the truth? Is the street really narrower at the farther end or does it only seem so? Is it a fact or an appearance? Indeed, every one of the senses can be proved unreliable. Have you ever thought of this point, that the physical senses give no evidence of anything that is indestructible, permanent, immortal, and that they do not perceive the truth? Any material object can be disintegrated and destroyed… or be reduced to energy or force, in other words, a mere theory.
Now take the case of a truth like two times two are four. That mathematical idea is an actual fact; it can never be changed or destroyed, can never decay, lose its power, truth or life, always has been true and always will be. Neither is its existence or truth dependent on the figures with which it is expressed, or upon the schoolboy who sincerely believes two times two are five instead of four. This mathematical idea illustrates the indestructible and eternal nature of an idea of truth. Now can this idea be perceived by the material senses? No. They see but symbols which represent it, not the idea itself. If the idea were in the figures, everybody could see it who sees the figures, but to the ignorant these do not reveal the idea. Thus truth is not seen with the physical eyes, but with the understanding, which is a faculty of being entirely apart from the five senses. For the same reason, the fact that two times two are four cannot be felt, heard, tasted, or smelled. The material senses do not perceive it, nor can they perceive truth in any form. They are conscious only of their material beliefs, and nothing else. If these senses are so unreliable and are so incapable of perceiving truth, why should we place such confidence in them? The sooner we stop believing them and base our understanding on absolute truth, the better.”
by Hermann Hering, 1909