Agarwood

Healthy Aquilaria wood is pale, light and worth almost nothing. Agarwood is what the tree makes when a particular mould gets into a wound: the heartwood floods the damaged area with a dark, dense, aromatic resin, and over years or decades that infected section becomes the most valuable raw material in the perfume trade. Grade the resin high enough and it outprices gold by weight.

That origin explains the economics and most of the problems. Only a small proportion of wild trees are infected, there is no way to tell from outside, and finding the resin means felling the tree. Wild Aquilaria across South and Southeast Asia was cut to the point that the whole genus is now listed under CITES, and most legal supply comes from plantations where trees are deliberately inoculated, drilled and infected on a schedule.

The names are worth keeping separate because the traditions behind them are. Oud is the Arabic, and in the Gulf a chip burned on charcoal for a guest is ordinary hospitality rather than ceremony. Jinkoh is the Japanese, and there the material is not burned but heated on mica over ash so that it never smokes. Chen xiang, sinking incense, is the Chinese, and the name is a grading test: the best grades are so loaded with resin that they sink in water.

Sanskrit agaru sits behind all of them, and the trade routes that carried the word carried the wood.

The Japanese art of kodo is usually translated as the way of incense, and its central verb is not to smell but to listen. A chip of agarwood is placed on a piece of mica over a bed of prepared ash in a small cup, heated so that it releases scent without burning, and passed around. Participants hold it, listen, and pass it on.

What is being done is a game as much as a meditation. In the kumiko form, several scents are heated in sequence and the participants must identify which are repeats, recording their answers in writing. Many of the games are keyed to literature: a set of figures drawn from the chapters of the Tale of Genji is the standard notation, and getting the answer right is partly a matter of knowing the text.

The classification system is old and strange. Agarwood is sorted into six countries and five tastes, rikkoku gomi, the countries being trade origins and the tastes being sweet, sour, hot, salty and bitter. A named piece of agarwood can be an object of state. Ranjatai, a fragment held at the Shosoin repository in Nara since the eighth century, has been cut by Ashikaga Yoshimasa, by Oda Nobunaga and by the Meiji emperor, and the cuts are labelled.

Kodo sits with tea and flower arranging as one of the three classical Japanese arts, and it is by some distance the least practised of the three.