Four walls can depict anything in our lives. It can be anything. Even a lonely person's ming if you ask him can be said to be closed inside four walls of darkness and even a wedding ring can be said to be kept inside four walls of a well decorated box.
The four walls...
The four walls means closed in its general sense. I spent some time today to think about it. What does four walls or closed inside four walls mean to us? For everyone the difference would be varying. I spent in recent times some time with my friends to ask what blankness means to them. The exact question was like this, "Consider your mind to be blank and without thoughts, what color does it bring to your mind?". Thus I could figure out the basic character of my friends. Many said White, then others said grey and finally i thought it for myself which was 'Black'. If at some point I get a connection between the characters and the colors then I can easily understand that I am the darkest guy among my pals. Its true. My thoughts are dark and my character is dark which I try to cover to an extend. This post is not a confession if the readers think so, it is just that I have taken myself as an example to explain me, myself.
Thus according to me the four walls have got a philosophical meaning. The color which you choose for your house is the mirror of who and what you really are inside. The color of the room in which you choose to live actually represents the hidden character in you. However you try not to do it, this character of yours will frame the decisions in your life. It is very vital for your success in life.
So what we have to do is to nurture the true yourselves. We should understand who we really are and what you really are. The funny part is that your true color or your true wall color will just help you even if it does harm to others. It will never hurt you. So be yourself before you try to follow someone's nature.