My son is 7. He loves dinosaurs, buttered pasta and a dog called Frisbee who doesn't exist — he's been talking about him for two years. In ten years, he'll have forgotten every one of these details. Unless I've written them down somewhere for him.

The time capsule is not a new idea. Objects buried in gardens, letters sealed in drawers, metal boxes tucked beneath the foundations of a building — humanity has always had this urge to speak to the future. What has changed is that we can now do it digitally, collectively, and without the risk of the box rusting or being lost in a house move.

For children, a time capsule means something particular: it's a message sent to themselves, or received from their parents, from a past they aren't yet truly aware of living. It's a way of travelling through time.

What to put in a capsule for a child

The question of content is often intimidating at first: what do you put in a time capsule? In practice, it's the most trivial everyday details that become the most precious over time. Not the big events — the big events, we remember. It's the small things that vanish.

What he eats at lunch. What he says when he's happy. The way he runs. The name of his best friend at school, and why they fall out sometimes. His fear of thunder. The song he sings in the bath and makes up as he goes. The exact sentence he said one Tuesday morning in March that made you laugh until you cried.

Alongside the words, photos play a central role. The bedroom with its posters. The school bag. The favourite toy that will be forgotten in three years. The neighbourhood where the family lives, the familiar streets that seem like nothing but make up his whole world at that age.

And the voices: an audio message recorded by the parents, by the grandparents, by an older brother or sister. A voice saying something simple — “right now you're 7, you love...” — that the child will rediscover at 18 with an emotion hard to anticipate.

The collective capsule: the whole family writes

A time capsule for a child can be individual — a single parent writing alone — or collective. The collective version has something richer about it: several points of view on the same child, at the same moment in their life.

The maternal grandmother describing what she feels when she sees him arrive. The schoolteacher asked to add a few words (some parents dare to ask). The godfather who lives far away and recounts what he remembers of their last visit. The older sister describing her little brother with a precision that is both relentless and tender.

This collective portrait, seen by a dozen people who all loved him differently at that precise age — is something you cannot rebuild after the fact. It requires having been gathered in the moment.

When to open it — and how to set the date

It's one of the most important questions: when does the capsule open? There's no rule. Some families choose a symbolic birthday — 18, 21. Others a date tied to an event: the end of secondary school, a wedding, the arrival of a first child.

What matters is setting the date at the moment of creation and noting it somewhere reliable. A digital capsule can be locked until a given date — the content is there, but no one can view it before the appointed time. There's something magical about this mechanism for children who grow up knowing that something exists for them, somewhere, that they can't open yet.

The waiting is part of the experience. It isn't an album you browse on demand. It's a chest with a lock and a date engraved on it.

What adults feel when they open a capsule from their childhood

Families who have already lived through this moment describe an experience that is hard to predict. Reopening something created ten years earlier means coming face to face with a version of yourself you can barely recognise. The tastes, the fears, the friendships of the time — everything feels at once familiar and foreign.

And the voice of the parents — recorded when they were younger, when they were still of an age to speak with that lightness — is something that cannot be reproduced. For some, this moment is one of the most powerful of their adult life.