The shelf has no line across it

Stand in front of the shampoo shelf in a supermarket in Helwan and your head has already sorted it. These are the expensive ones. Those are the cheap ones. This is imported, that is local. Premium at eye level, value down by the knees.

It is a convenient way to see it. It is also mostly wrong.

Walk the shelf slowly and the categories dissolve. There is a local brand priced above two imported ones. There is a mid-priced bottle with a pack that looks expensive and a formula that does not. There is a cheap one that some families have bought for twenty years because their mothers did, and to them it is not cheap at all, it is simply the right one. Between the dearest bottle and the least, every step is small. There is no point where premium ends.

Treating the shelf as two boxes does damage. It makes a brand think it has only two choices, this box or that one. It makes it dismiss the shopper who buys from both ends of the shelf in the same month. It hides the very places where something new could fit.

The truth is less tidy. The shelf is one long line, and every bottle on it sits somewhere along that line, which shoppers walk up and down depending on the week, the occasion and who the bottle is for.

That makes the job harder, not easier. With two boxes, you just pick one. With a line, you have to decide exactly where you are going to stand, and why there, and not a little higher or a little lower.

That decision is the work. The boxes were only a way of avoiding it.