I'm not going to tell you, "Show me your friends and I will show you who you are."
I'm not going to tell you, "Bad company ruins good manners."
I'm not going to tell you, "A friend to all is a friend to none."
I'm not going to tell you, "If you choose bad companions, no one will believe that you are anything but bad yourself."
I'm not going to tell you, "Friends and money are like oil and water; you will lose both when you mix them."
Did you know that the movie Tarzan is an adaptation of a book, Tarzan of the Apes by Edgar Rice Burroughs?
I have been lucky to have read the original book, and I find it better than the movie. I got a couple of life lessons from the book. Like on friendship.
When Tarzan met Jane Porter and began embracing his human nature, learning to do things the human way. He suddenly found himself out of place among his friends: the apes and the elephant he grew up with. He became very bothered and began thinking about the whole thing. Then he came to this marvelous conclusion: that we do out grow some friendships, that as we change we will have a tough time sticking to the same friends.
The easiest friends to have are the ones we attract, the ones we share similarities with. They let us be ourselves. We don't have to change to keep them because they became our friends as a result of who we are. The only trouble is that we are constantly changing/growing. And soon the friend you could share your deepest concerns with, changes in ways you do not expect. His ways and thought patterns are now strange to you. So your circle of friends will always keep changing: easy close friends will become annoying close friends, and then longtime friends we seldom visit.
Only few people have life-long bosom friends. And in some cases, the other person has stopped considering the one as a bosom friend. The feeling isn't mutual. The friendship is heavily one-sided: one person asking all the time, calling all the time and initiating all the activities in the friendship.
Then there are a lot of people trying to keep up with friends. They make inconveniencing adjustments, always keeping in touch with everyone, present at every friend's event, never letting go of anyone. They give up too much for the sake of friendship. They won't let things follow their natural course. They have the toughest kinds of friends. The friends that don't care about staying in their lives. Friends that have moved on.
So I call it: your friends, your life.
Just as the course of your life chooses friends for you (your easiest friends), so also the friends you force yourself to stick with alter the course of your life (your toughest friends).