I have a dream about places that I never visit nor I heard of, and the guy who invited π did not roamed the earth and the guy who invented the number decillion never had or saw anything that has this value.
Any number can be discovered once you understand the base number system. That guy probably saw that one hundred of something was more than ten of something and his brain figured it out as he slept. The next guy who "discovered" ten decillion did not need any additional experience.
As for your dream of a place you have never visited of heard of - tell me how you know it wasn't just a collage of previous landscapes you had seen?