A laid hedge is a row of trees that have been cut almost in two and told to carry on.

The hedgelayer takes a billhook to each stem near the ground and chops downward, more than half way through, until the stem will bend. What is left is a hinge: bark, a little sapwood, the thin layer underneath that does the growing. The stem is pushed over to about forty-five degrees and laid along the line, and it lives. Sap crosses the hinge as it did before. In spring the laid stem throws new shoots up along its whole length, and the gap beneath it, where an animal used to get through, closes.

Cut too shallow and it will not bend. Cut too deep and you have firewood. The craft is the width of that tongue.

Hedgelayers lay uphill. Sap rises, they say, so the trees keep climbing through the wound. And they lay in a dialect. The Midland style, meant for cattle, keeps its brush on the field side, so a ton of bullock leans into old thorn rather than new shoots. The Welsh Border style packs the finished hedge with dead wood, because sheep nibble. Devon puts the whole thing on top of a bank. The society that keeps the craft counts around thirty-five styles, some belonging to a single estate. You can read the animal off the fence.

Then it grows out, ten or twenty years, sometimes fifty, and someone comes and does it all again.

I keep coming back to the arithmetic. The fence works because every tree in it was nearly killed, and the only thing still joining each one to its roots is the part the blade decided not to take.

To get a gardenia into a bottle the old way, you have to kill the gardenia. Pick it, then drive the scent out with heat or pull it out with solvent. Both rewrite what they capture. The most volatile molecules — the top of the smell, the part that reaches you from across a garden — are the first to go, and what ends up in the bottle is a near relation produced under duress.

Roman Kaiser spent a career at Givaudan on the alternative. Seal a small dome around a flower still attached to its plant, draw the air off through an adsorbent trap, then run what you caught through a gas chromatograph. Nothing is picked. He carried it into rainforest canopies, up the European Alps, across the Cape and the Hawaiian islands, and worked through roughly five hundred endangered species.

No part of that stores a smell. What comes back is a list: these compounds, in these proportions. Scent of the Vanishing Flora describes 267 of those species and closes by summarising their analytical compositions. A perfumer can read the table and build the scent out of bottles on a shelf, not one of which has been near the plant.

I keep turning over what kind of record that is. A pressed flower is the thing itself, dead. This is closer to a score — instructions that were never the thing and cannot wilt. For the species on the list that do not make it, the score is what is left standing: a smell anyone can produce, accurate the way a translation of a lost poem is accurate.

The final piece of cake acquires rules that did not apply to the rest of the cake.

Earlier, you could simply take some. Now taking it means finishing it, and finishing it makes an announcement about everybody else's appetite. You are volunteering to decide that they have had enough.

I find the usual compromise — cut it in half — almost unbearably funny. It preserves the possibility of cake for another person while reducing that possibility to a smaller and smaller physical object. Nobody has to admit to wanting the last piece if the last piece can keep being manufactured.

There is care in this. There is also a little vanity. Leaving something for others and being seen to leave something for others make exactly the same crumbs. I don't think anyone at the table needs to sort out the proportions.

What interests me is how an offer changes the situation. "You have it" can make the cake edible again. The amount of hunger hasn't changed; somebody has just taken responsibility for the ending. I prefer that small bit of bossiness to the indefinite public display of restraint.

The cake is now too small for a fork, but someone has gone to find a knife.