There are places that are hidden from you, not by being concealed physically, but by your own habits. You only take certain ways, turn around certain corners, look into certain directions, and when you are in your familiar environment, there might be some perfectly accessible places only a few steps away of whose existence you don’t have the slightest idea. Maybe there is a street, a square, a park just around one or two corners, and you have never been there in all those years and you don’t know that place is there.
A stranger coming to your area might soon know it better than you because he does not have any habits blocking his views and ways. And even if he does not find every place immediately, every place nearby retains the same likelihood for him of finding it. If you live in the area for a long time, on the other hand, you develop systematic blind spots.
The same phenomenon can be encountered in the area of thinking. New ideas often come from outsiders and newcomers. Children, the ultimate newcomers to this world, often surprise us with their unexpected views. Later in life, and especially in fields of expertise, we become less flexible and develop blind spots. Sometimes, after problems have been solved and solutions turn out to be very simple, people might think: “why didn’t we see this earlier?” This is the blindness of experts, often also institutionalized as organizational blindness.
In the area where you live, you may go for a walk and deliberately turn into the streets and alleys you have never taken before. You may deliberately look at things to search for things you are overlooking all the time. Suddenly, you see shops, balconies, trees, entrances that you have never consciously perceived before.
In your thoughts, you can likewise train to consciously see the patterns of thought, the unexpressed premises. It takes some training but then you will start to see possibilities you might not have seen before. Many will turn out to be blind alleys, but you might hit upon completely new ideas. To a great extent, creativity is the art of taking different turns. You might get lost or enter dangerous areas, but it is worth taking the risk.
(The picture is from http://commons.wikimedia.org/wiki/File:Durchgang_in_Rheingoenheim.JPG.)