I think I cannot give you anymore reasons than I already did. You still believe you perceive the object, while you only perceive your senses. If you realize that, you will know you don't know what is really there. I could try to explain more, but it would only complicate things. I think examples I already gave are clear enough if you ponder them. If you just skip them because you don't quite get them then conversation on that subject cuts there, since you don't know my point of view. Numbers, functions, etc, you say are human creation. So are the words. What would you think the 'tree' is if you couldn't speak ? What would you see? When you see something with your senses, you have concept of what you see. Thus you are not really looking at the object, but you react to concept of it. This can be pleasnat or umpleasant. I gave you example of rock changing into a tree when you close your eyes. What if it was something beautiful to you, then changed into something very scary ? The object is the same, the concept you react to is different. Since you instantly react to concept you may have no time to actually perceive the object. We just 'like' or 'dislike' the concept. But as buddhism says, there is third way, 'middle way'. Which I believe is actually looking at the concept. Once you do it, it loses any ground to exist as real, because it is not what you see with your senses, it is what you create with your mind. Thus, some people practice meditation, which allows relaxation and free passing of thoughts. Given enough time you stop craving thoughts, which absorbs your attention, and when flow of obscuring thoghts passes you perceive the object. In some cultures ability to perceive object is called 'third eye'.