I do not know if he was crazy or not, because I was the one to ask this question... however from the answers above, I do not believe that he was crazy. hHe was just extremely smart, so everybody else called him crazy.
No he was a smart man.
We are all crazy at some point. We have abilities & disabilities.
He was a slow talker & learner. He couldn't remember names & numbers, he never learnt to drive on his own, but he was a genius of science, so many parts of today's science is progressing by his theories, the theories that not much people cared when he was alive.
And the stories you might have heard about not remembering his wife or his low memory in these subjects, it's normal, when you focus so strongly on one topic, the brain can't connect to other things.
And the meaning of the crazy that you looking for doesn't exist. All crazy humans that people call crazy aren't crazy, they become crazy because this is how people decided to look at them.