In-sane...?

I'm in the midst of reading a book by G.K. Chesterson called "Orthodoxy." It is a book talking about why he (Chesterson) chose Christianity and what led to his conversion. So far I'm only a chapter and a half way through the book. The first chapter talked about people who are in-sane and those most prone to someday go in-sane.

He mentions that people who are most prone to go in-sane are those who believe that everything must be worked out logically and/or reasonably. He backs this up by saying that not everything can be explained through science or pure logic. Because of this, those who depend soley on logic and reason will in the end go mad! Even some of the greatest thinkers in the world such as Socrates, or Aristotle didn't figure everything out!! They believe that if it can not be figured out logically then it is either not true or not worth talking about. However, knowing that there is something out there that they can not explain, will gradually begin to nag at them.
By adopting this type of thinking, they tend to live in this tiny universe where anything unexplainable is not allowed in. This eventually leads to the hospital for the insane.

The book has been great so far! I hope it only gets better from here.