Human beings make a big deal about being normal. We’re probably the only species for which it’s normal to think you’re not normal.

Every society operates under thousands of unspoken rules, and when you break them people get nervous. There are acceptable and unacceptable ways to stand in line at the bank, order at restaurants, and answer the phone. There are appropriate and inappropriate birthday gifts, wedding toasts, and hugging styles.

Every type of social situation has its own subsection of laws and procedures. You can make everyone around you instantly uncomfortable just by facing the back wall while riding an elevator, or asking a fellow bus passenger if they want to hear a story.

Miraculously, most of us have learned most of these rules by the time we become adults, at least enough to fulfill our basic responsibilities without causing a scene. The moment kids are born, they begin to absorb clues about what’s okay and what’s not by continually watching and emulating.

We learn some of these rules in explicit mini-lessons from our parents and teachers, and occasionally friends, when they pull us aside and tell us, “We don’t talk about pee at the dinner table,” or “We don’t bring up sports betting around Eddie.”

We also learn the location of certain boundaries when we bump up against them, by remembering which acts triggered dirty looks, and which got laughs, or no reaction at all. Over time, we learn that we can avoid awkward and painful collisions with these boundaries by simply doing what other people are doing, and not doing what they’re not doing.

Stand where the other people are standing. When other people are quiet, be quiet. When they’re eating, eat. When they’re being somber, be somber. When they laugh, laugh (even if you don’t get the joke).

This survival tactic eventually becomes a part of our worldview. Humans are an easily frightened, highly social species, and we put together a sense of how things are supposed to be—of how we’re supposed to be—by what seems normal for the people around us. How do you know if you’re in good health for someone your age? For some places and times in history, failing health at age 48 is expected; in 21st-century USA, it means something’s gone wrong.

Every life is mostly private

Our reliance on using norms for guidance gets us through a lot of confusing social situations, but it creates a huge problem when it comes to evaluating ourselves.

We can’t compare ourselves to what we can’t see, and most of a person’s life is invisible to everybody else. Our thoughts, feelings, moods, urges, impressions, expectations and other intangible qualities happen only on the inside, yet they constitute the largest part of our lives. They aren’t just important to us—essentially, they are us.

Life is ultimately a solo trip, and most of the landscape is mental. Even when it comes to your closest loved ones, you never get access to another person’s internal experience. They can talk about it, or hint at it through their actions, but everything behind their eyes is fundamentally off limits to you, while to them it’s everything.

Our public selves are that one-tenth of the iceberg that sees the Sun. The other 90% is who we are only to ourselves, and we have nothing to compare it to. You can’t tell, just by observing, whether other people have a similar inner world to yours, especially socially unacceptable feelings like intense guilt, or feelings of incompetence, or apathy, or uncontrollable sympathy.

One of the behaviors we learn to emulate is to always present our “best face”, so we learn to keep our most insecure and ugly thoughts to ourselves. This leaves a lot of us wondering if we’re crazy, or especially messed up inside.

Many of the emails I get from readers are private disclosures that they feel like impostors: they have successfully fooled their friends, family and co-workers into thinking they have things together, but they’re only pretending. Their stories are so similar it’s almost unbelievable. Usually they have a respectable-sounding career and home life, but they feel particularly fragile and troubled compared to how everyone around them appears to be.

My answer is always that I feel that way too, or at least my own version of it, on a regular basis. Hearing these stories over and over has all but confirmed my suspicion that human beings live with a consistent discrepancy between what we’re each like in our private world, and what we think others are like.

Somewhere along the line, human beings have convinced themselves that the normal way for a grown human being to feel is prepared, secure and competent. Serious feelings of anxiety, incompetence, guilt or insecurity must always mean something’s wrong with you—either there must be some past life event that justifies these feelings, or you’re just crazy.

You might get comforting glimpses of the dark, bulbous root of someone else’s iceberg by reading Sylvia Plath poems or Cormac McCarthy books, but in social situations it is as hidden (and as officially non-existent) as the Pentagon’s security schedule.

You’re on your own but you’re not alone

The other day on Reddit, someone asked any therapists and psychologists in the audience to answer a question: What is something that most people think they are alone in feeling/experiencing?

Dozens of therapists answered, and hundreds of people learned that their unique inner problems weren’t unique and might not even be problematic. They’re just hard to see in others, because most people never share them, except maybe with a therapist. (The thread is definitely worth a read.)

The “Impostor syndrome” I mentioned was a really common one. So if you’re the one who thinks their entire career is a fluke and that it will all soon be exposed in a nightmarish intervention scenario at your office, you are not alone.

A lot of perfectly sane people have deep insecurities, dark thoughts, and peculiar aversions to everyday things. Intrusive thoughts, about sex, violence, humiliation, suicide, the end of the world—not at all uncommon.

We all have our own craziness going on, but we’re very good at hiding it from everyone else. While some of our neurotic patterns are serious enough to warrant treatment, a lot of it is quite normal.

All of our personal dilemmas and life situations aside, simply being human is just plain hard. We want to make it look easy though, because almost everyone else does. But if you could look right down through everyone else’s iceberg—if you could see exactly how much insecurity, stress and craziness there is hidden in the average office floor or subway car—you might be glad for your own.