In fact, most people don't understand the Relativity. Most still rejects Evolution. It wasn't easy to understand the Copernican system in the Galileo's time.
It is easy to understand for a handful, and it seems obvious only to a few, when a new major breakthrough is made. Galileo was wrong. It may be easier, but not "easy to understand once a truth is revealed".
It wasn't easy to understand the Copernican system in the Galileo's time.
I suppose people didn't understand it because they didn't want to, not because they couldn't manage to. (Same with evolution -- what the OP was about. I might agree about relativity, though I guess for some people at least the absolute denial macro does play some part.)
Galileo was wrong.
More like stuff that was true back them is no longer true now.
Here's the new thread for posting quotes, with the usual rules: