Have you ever been invited to a friend's house and discovered immediately after stepping inside that it smells like an episode of Hoarders? Maybe it's dirty clothes, maybe it's last night's Panda Express, maybe it actually is a dead animal somewhere inside the walls, but in any case, you wonder the same thing: Can he not smell this?
Well, no he can't. I believe the saying is, "A fox can't smell its own hole." Fact is, to him, his house just smells like air. He's immersed in it! It's difficult to notice incremental changes that occur over time within the only environment you're exposed to. But to an objective outsider, as you are to your friend, these changes are obvious. Should you tell him? What exactly is your duty as a friend? Is it to always do and say what makes him happy? What if it's going to make him feel bad?
This brings me to the philosopher Plutarch. Everybody wanted to be his friend. He was a rich man who had a prominent standing in local politics during a time when most people lived in chaos and uncertainty, making him comparable to the cow that was lowered into the Velociraptor pit in Jurassic Park. A lifetime of disingenuous friendships levied by people trying to take advantage of his stature in society left him with a lot to say on the value of friendship. In his essay "How to Tell a Flatterer From a Friend," he makes the case that friends are absolutely crucial for realizing our potential in every area of our lives, including happiness.
Plutarch said that it's easy to delude ourselves; we do it all the time. Your friend doesn't realize that his house smells like the city dump because he is immersed in it. Similarly, we can be immersed in our own inefficient or destructive patterns of thought to the point that it takes an objective outsider to tell us we're being an idiot. Who else can we truly rely on to be an objective voice without exception?
Sometimes we need someone to look at us and say, "No, you're not going out in public wearing that leather fanny pack. I don't care if you're trying to be ironic."
Imagine if the only things you were ever able to improve on were things that you were not only perceptive enough to notice, but honest enough with yourself to acknowledge. To return to our example from before, not only would Plutarch say that you should tell your friend about his house, but also that if you don't, you run the risk of being the opposite of a friend: a flatterer.
If the value of a friend lies in his honesty and the various ways that honesty enriches our lives, then the danger of a flatterer lies in his dishonesty and the various ways that dishonesty destroys our lives.
Plutarch thought of flatterers as parasites. By definition, a parasite is an organism that lives by consuming nutrients at the expense of its host. This really is the difference between a friend and a flatterer to Plutarch; it was a question of motives. A true friend always acts in your best interest, no matter the cost to you or them. A flatterer always tries to please you, regardless of whether or not it's in your best interest, because they want something from you.
Plutarch writes, "The flatterer is always covertly on the watch for some emotion to pamper. Are you angry? Punish them. Do you crave anything? Buy it. Are you afraid? Flee. Are you suspicious? Give it credence."
In modern times, our definition of friend changes based on the context in which it's used. If a flatterer is someone who falsely represents themselves for personal gain, then we've created a social media landscape that actually encourages their existence. We encourage people to post only complimentary, smiling pictures of themselves as though they never experience pain. We encourage people to stand up for what they believe in and click a pixelated "Thumbs Up" to show their undying support for the most recent bout of activism posted by people not sitting on their couch. We encourage the creation of a webpage that's a false representation of yourself -- an alter-ego -- so that you can control it, and interact with the alter-egos of everyone else.
Plutarch would have pointed out, "Yeah, this person has 900 friends on Facebook, but how many of those people are being totally honest with them? How many of those people can they truly say are always working in their best interests, and how many of them are just parasites that occasionally please them?"
One week of correspondence with someone who is truly your friend will contribute to your personal growth more than the sum total of every New Years resolution you will make for the rest of your life.