Just friends

"The only way to have a friend is to be one..."
I read once that we all keep our friends for personal benefits. When we realize that a person can't bring us any other favors, we'll let it go off our list of friends.
Just think of your amigos, aquintances, friends, good friends, best friends. Why do you consider them friends? Maybe because they are nice to you, maybe because they listen to you or help you when you need, maybe they make you feel important?....
Are we friends because we help/like/listen to each other OR we become friends after we help/like/listen to each other? I have no ideea.
Maybe beeing nice/listening/helping all the people around you, eventually you will find people with same values who will turn into your aquintaces, then friends and good friends or...maybe not.
Real friends are like precious jewels. Very hard to find.