Why is it that when someone tells you that there are over a billion stars in the universe, you believe them, but if they tell you there is wet paint somewhere, you have to touch it to make sure?
Because I can tell by looking at them that I am not capable of counting the stars in the sky. So, it becomes easily obvious to me that there are over a billion stars in the sky. But, I can't tell for sure that wet paint is wet by counting them and looking at them. I must feel it. This is why I need to touch it to make myself sure of it.