Human Mind Vs Rock Wall

I have often wondered why it is so difficult for people to believe in something that they can’t see or even have a picture of. I came to the conclusion that the human mind at times can be like a gigantic rock or a solid stone wall. A rock or stone wall is exposed to lots of rain every year yet little moisture is absorbed, the water just runs off the surface. The mind when closed likewise sheds information when closed without even considering its importance.