This was one of the advice I had received when I first starting reading books on motivation, improvement, and finance. I used to think it was easy to be receptive, since I did not know anything. I was only half right.
As the amount of books I read increased, I started to subscribe to some school of thoughts. This became a barrier. It is becoming tougher to keep an opened mind. Recently, I began reading a book on stock picking, based on growth investing and picking momentum stocks. Some of the theories stated were contradictory to those I have read before from value investing books. All of a sudden, I found myself debating against the theories of the book. As I was about to put the book away and write off the book as one being ‘senseless’, I was reminded of the quote above.
Remain open minded. You do not have to agree with everything you hear or read, but at least be open to the different school of thoughts. This way, you can learn about how others think, and maybe even take away some pointers which could be useful.