The single shelf

Here is a simple constraint: everything you use must fit on a shelf the width of your two hands.

It is arbitrary, and that is exactly what makes it useful.

Why a constraint of space

Because it forces you to decide.

Without a constraint, nothing is ever set aside: every product has a reason to be there, and there is always room for one more. That is how shelves fill up — not from an excess of taste, but from an absence of limits.

A limited space forces comparison, and comparison forces you to have a criterion.

How to proceed

Take everything out. Lay it on the table.

Sort by function, not by brand: what removes, what restores, what seals, what protects, and an “other” category that will be larger than expected.

You will immediately see two things: two or three occupants for the same role, and one role left empty.

The sorting, in order

What arrived for a problem that has since passed. A season, a reaction, a difficult month. The problem is gone, the product has stayed. This is the thickest layer, and the easiest to remove.

What duplicates. Two things that do the same job. Keep the one you prefer to use — that one, you will finish.

What is never finished. A product you repurchase without ever finishing the previous one has not found its place. It answers a worry, not a need.

What contradicts something else. One that takes and one that seals. One that refines and one that loads. This is the most useful and most difficult sorting, because you have to know which of the two logics is the right one.

What the exercise reveals

Most people who do it remove two thirds, and in doing so discover they never had a routine — they had an accumulation of attempts.

That is not a fault. It is what happens when you search without a criterion: every attempt is reasonable, none is ever withdrawn, and after ten years you have a cupboard.

The sorting you cannot do alone

The fourth one, the one of contradictions.

To decide between two opposing logics, you need to know which one suits your face: should you give back to it or take from it, nourish it or lighten it. Nothing on the shelf says so, and neither does the mirror — two faces that ask for the opposite often look the same.

This is the only point where the exercise stops, and it is the one that matters most.

It is resolved one step earlier: by knowing which logic you belong to, which can be read from the very beginning. After that, the single shelf is done in one evening, and it holds for years.