how to define friendship   

I often wonder what friendship is .friendship is too big a topic to talk about eitehr specifically or generally .I guess most of us are still in a puzzling state about what friendship is ,and I myself should be included .

maybe people who define friendship according to his own life experience will say that they have a good concept of friendship ,which I think is too narrow to get objective definition of it .

but how hard it would be to talk about friendship without mixing personal feeling in it ,especially when it comes to the matter of closet friends. so here i WOULD LIKE TO SHARE my views with you about friendship ,about my closet friend .
I have had friends since I was born ,some fo whom have come along with me through my life ,and it is impossible to always keep your friends around you since departure is one part of life that everybody must experience .though some of you may oppose me by exaggerating the connotation of the concept of being together always psychologically ,I still hold that departure is an absolute thing .how could it be possible that your friend always keeps you in heart as he had ,is having and will have different hearts .Man'heart is a quite strange thing .never think that one can wholly touch it ,sometimes our heart is so abstract that you dont even know how to get to them .if we take heart as a cube and closet friend a gentle breeze ,this breeze can only blow one facet of this cube from one direction and can rarely reach any other sides of your heart .I am not sure whether I have put it very clearly but believe me that there are no fixed closet friend in your life .with different time ,place ,emotion and situation ,you have different closet friends