What saying would you think of if you saw a picture of a closed door? This is the one that always comes to mind for me, but somewhere along the way, some wise person (or smart ass, depending on your point of view), decided there was more to it. The wise person in this case, I believe was my late sister. She always chose her words so well, especially when she wanted to get a point across.
If you have a few closed doors in your life, maybe you should give them another look..