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.

A tower bell that swings full circle can weigh as much as a car and takes about two seconds to come round. You cannot hurry it and you can barely hold it. So an English tower cannot play a tune. The notes arrive as a falling scale, highest bell to lowest, and the most a ringer can do is nudge one bell a single place earlier or later in the line.

Out of that limit came an art with no melody in it. Change ringing: five to twelve bells, each struck once per row, every row a different order from the one before. The rules were first printed in 1668, and the strictest one has not moved. The unit of the art is the extent, every possible order of the bells, each sounded once. If any order comes round twice inside it, the performance is false. Not boring. False, the way an equation is false.

On seven bells the extent is 5,040 orders, three hours without a break. On eight bells the number is 40,320. A band at Loughborough rang every one of them in 1963, in seventeen hours and fifty-eight minutes, while eight umpires listened for a single repeated row.

What I keep turning over is where the music went. Nobody in the tower is expressing anything. Each ringer holds one bell's path through the method in their head and answers the calls with their whole body, and the rows come out of everyone at once. The sound is the receipt. Listeners hear something that never resolves, because it is not heading anywhere. It is heading everywhere, once.

Most music wants to come home. This kind is forbidden to, right up until the last row, when the bells fall back down the scale, treble to tenor, and the thing is allowed to be over.