A few days ago I visited your father and mother at their lovely little apartment that I’m sure you know so well. I have recently made a point of sending my friends postcards when we have a nice time together, and your father suggested that I should write you a letter.

I spent a moment thinking about it — as surely by the time you would be able to read this letter, much time would have passed — and I settled on writing to you. I think there’s a lot to be said for having a letter written unambiguously to you, but to some earlier version of you; the littler Kasimir who doesn’t understand my words can keep them until they’re understood. Those thoughts carried into a future neither of us really know much about, Kasimir.

I thought next about what I’d tell you about the world. I’ve been to every continent, and more cities than I can name. I’ve sat down to talk to quiet but larger-than-life government ministers, had long hours to sit and work and talk with famous actresses for their front-page pictures; I’ve met the people that 007 would work for. I’ve had fallings out with overnight millionnaires over a bunch of flowers I gave to a friend; and I’ve partied late into a Dubai night at a lavish wedding under watch of armed guard.

The world is very big, Kasimir. Everyone will tell you that, and it’s true. There are more people out there in the world than you or I can possibly imagine in every possible flavour and colour and creed. And yet — it really is smaller than it sounds. You will meet one person, and then another, and another and you’ll realise that though there are so many of us, and we are so very diverse, we are rarely so truly unique as to be incomprehensible to another, even on the very other side of the world.

We are so different, but our differences are so shaped by our usual human wants and needs and experiences that I’m sure one day Kasimir you could sit as a stranger from far away on the doorstep of a Nepali townhouse, and in watching the people go by for an hour you could name the wants and needs and daily stories of all those around. If you watched for a week, you’d know their dreams and their goals, and their little heartaches they try to sweep away like the dust of an old room.

This is our blessing and our curse as people, Kasimir. We are all so different and yet so similar and so adept at simplifying and predicting that two best friends can say they know each other for a lifetime, and yet not really truly know each other at all.

I’m sure it sounds so odd and fanciful to say that we can not know each other and yet not know each other — but I’m sure you have seen a flower, haven’t you? We all know a flower! You might even know that the plants breathe out things we need to breathe in to survive — do you know they breathe out the same things as us when it’s night and the sun isn’t around? Or that they’re made of uncountable tiny little living things shaped like bricks, which fill with water to hold themselves up? Do you know the petals of a flower — those little pieces which give it colour — were once green leaves on that flower’s great-great-great-great-great-great-great-great-great-grandparents? They learned to make flowers from leaves ever so slowly, generation by generation.

The way we can say we know what those flowers are and yet they’re so completely filled with tiny little things we don’t yet know is the same way the world can be so big and yet so small, or that a person can be so knowable to you and yet unknown.

Your parents I’m sure will teach you to say “please”, and “thank you”. They’ll teach you that it’s polite and kind; and one day, you’ll give someone flowers and say “I’m sorry”, or “I love you”. As you grow up, you’ll find in the moments that matter most you’ll look at someone who really cares for you and say “I’m sorry”, and you’ll see both that they’re happy to hear these words, and see in their eyes that they wanted to hear something more.

These prescribed things we say to each other are little ways that we show to each other that we know the other person. When you want something and don’t feel that they owe it to you, you say “please” — and when you bump into someone and realise you’ve inconvenienced them you acknowledge it by saying “sorry”. Some very human part of us feels seen; the hurt of the bump is noticed with a “sorry”; the kindness of the gift is noticed with a “please”.

The truth is, Kasimir, there is so much complicatedness inside each of us that someone long ago (I think) came up with these words so that we could say them without having to truly, really, understand. After all, most of the time people don’t really want you seeing them really truly. Perhaps they had a particularly bad day and so that little bump was all the more hurt for them, but a “sorry” will suffice.

But one day, as I said, someone will want more than that — and they probably won’t say. It’s hard to say because we are never taught that want, it comes from deep inside of us. Maybe that someone who wants it will be you. The real answer is perhaps the most important thing in the world, but it is also one of the hardest — because it takes so much of your time and your thought.

The real answer is to show that you know that person, and you understand. When you see a flower, you will point and say “a flower!”, but deep down we want to be recognised — maybe the first step is to say to that flower is “a rose!”, but as you will learn there are so many different roses out there. Perhaps that is the rose you grew from seed one spring because you saw it on the internet; perhaps it is your favourite rose. If you lost your favourite rose that you grew from seed one spring because you saw it on the internet — wouldn’t there be some small, sad feeling if someone were just to say that you lost simply “a flower”? People are this way about themselves.

One day as your parents taught you, you’ll say “thank you” for something you really wanted; and one day, you’ll give someone flowers and say “I’m sorry” when you really hurt someone, or “I love you” when someone really means so much to you — and that other person will, whether they say it out in the open or not, wonder “why?”. Perhaps they will have a small idea of why already. When this time comes, you must take a moment and think:

Are you thankful because they had to go so far to get that thing for you that you wanted? Or because that other person had to think so much to choose it for you and it was just right? / Are you sorry because you know you hurt them and you made a mistake? Are you sorry because you had said you wouldn’t, and yet you did? / Do you love them because they make you smile? Do you love them because they know just what foods to pick out for you both to eat?

This is my gift to you, little Kasimir. It is a big adult lesson that life has taught me over my 32 years. You can climb mountains if you choose; you can make a lot of money, and fly to a lot of places. You can learn 20 different languages; you could discover a new technology. None of those things, however wonderful, can be exchanged for knowing the right answer to this question; but if you can answer it right — if you can always answer it right — you will always have friends, and friends can help you climb mountains.