Unlike many everyday aperitifs, absinthe was historically almost always prepared and drunk in a highly specific way - this, the so-called "absinthe ritual" was part of the reason for its popularity and for the unique position it's always held in the pantheon of drinks. The classic French absinthe ritual involves placing a sugar cube on a flat perforated spoon, which rests on the rim of the glass containing a measure or "dose" of absinthe. Iced water is then very slowly dripped on to the sugar cube, which gradually dissolves and drips, along with the water, into the absinthe, causing the green liquor to louche ("loosh") into an opaque opalescent white as the essential oils precipitate out of the alcoholic solution. Usually three to four parts water are added to one part of 68% absinthe. Historically, true absintheurs used to take great care in adding the water, letting it fall drop by single drop onto the sugar cube, and then watching each individual drip cut a milky swathe through the peridot-green absinthe below. Seeing the drink gradually change colour was part of its ritualistic attraction.

The "ritual" is important - it's part of the fascination of absinthe. No other drink is traditionally consumed with such a carefully calibrated kind of ceremony. It's part of what lends absinthe its drug-like allure (for instance, one talks about the dose of absinthe in the glass, a term you'd never use with whisky or brandy). From all historical evidence, it seems that absinthe was almost always drunk like this - even the poorest working man, in the roughest bar or café, would prepare his absinthe slowly and carefully. It was seldom drunk neat (except by the kind of desperate end-stage alcoholics who might also be drinking ether or cologne); the water was always added slowly not just sloshed in; ice was never added to the glass.

The water added to the absinthe dose must always be iced, as cold as possible. Part of the advantage of using an absinthe fountain was that you could add ice cubes to the water to keep it cold, and some carafes had a chamber for ice as well. There's a famous poem by the French author and absintheur Raoul Ponchon, where he says if you add tepid water, you might as well be drinking ….pissat d'âne / Ou du bouillon pointu - donkey piss or an enema broth. Paradoxically though, ice wasn't added to the glass itself - the idea was to start with the drink as cool as possible, but let it slowly warm to room temperature as you drank it. Aside from historical considerations, it tastes better this way. It's essential to add the water as slowly as possible - drop by drop - particular at first, as the louche starts to develop. There are two reasons for this: it enables you to admire the gradual change of color, and it allows the aroma to develop slowly for maximum complexity and interest. (Technically: different essential oils precipitate out of the solution - and thus release their aromas - at different dilution percentages. By pouring very slowly you effectively get to appreciate them all individually, whereas if you just throw the water in everything gets released at once).

Holding the carafe in a relaxed and stylish way high above the glass, and letting the water slowly drip out drop for drop is harder than you'd think, and was a much admired skill at the time. Busy cafés had "absinthe professors" - professional absintheurs - who for a small sum would instruct a patron in the art, or assist him themselves. A slightly easier but also historically accurate method you might prefer is as follows: Place a sugar cube on the spoon. Drip a few drops of water on to the sugar cube, just enough to saturate it thoroughly. Then do nothing, just watch the sugar cube for a few minutes. It will spontaneously slowly start to collapse and drip into the glass, eventually leaving only a few drops of sugared water on the spoon. Then add the rest of the water in a thin stream.

Sugar isn't essential - it's entirely a matter of taste. In their brochures, Pernod Fils suggested their absinthe could be drunk with or without sugar. There is - or certainly was - an ingrained French predilection for sweet anise flavored drinks, cultivated from childhood with syrups and cordials. Most Belle Epoque absintheurs added at least one, sometimes two or even three sugar cubes, and some added gum syrup as well. Today we're likely to find this far too sweet. I'd suggest using half a sugar cube to start with, and then adjusting upwards or downwards according to preference.

The correct dose of absinthe is about 30ml - just over an ounce. Add three parts water to one part absinthe and then taste. For casual drinking ( as opposed to tasting a rare bottle) you might prefer to add a little more water, bringing the ratio up to 4:1 or even to 5:1.

Overall, it's worth taking the trouble to prepare an absinthe in the traditional way like this. The slowness and care required help put one in the right frame of mind to appreciate the subtleties of the drink, and it undoubtedly tastes better this way as well.

There is some debate amongst absinthe historians as to when exactly the traditional absinthe ritual originated. Certainly, there is no evidence that it was ever normal to drink absinthe neat, without water. Absinthe was drunk with the addition of both water and sugar from at least the 1850's, and probably earlier. Absinthe was by no means unique in this respect - 19th century drinkers had a far sweeter tooth when it came to alcohol than we have today, and other drinks and cordials were also regularly sweetened with sugar. They were usually served with a long cordial spoon or a kind of swizzle stick, to help dissolve the sugar. The use of a perforated spoon specifically for absinthe was a later development, which appears to have originated in the 1880's and only became widespread in the 1890's. From the 1890's onwards, it seems, on the evidence of existing engravings and cartoons, almost all absinthes in bars and cafés were served with a perforated spoon.

An occasional alternative to the perforated spoon was the brouilleur - a small metal or glass bowl that sat on top of the glass, and which, when filled with water, automatically dripped sugared water into the dose at the required rate. Some of these brouilleurs incorporated unusual refinements - one model in particular seems to have been designed to add absinthe to water, rather than, as usual, water to absinthe. But their use, although fairly frequent, was never remotely as widespread as that of the perforated spoon.

A popular alternative to using crystalized sugar (une absinthe au sucre) was to add either gum syrup (une absinthe gommée) or sweet liqueur d'anis (une absinthe anisée). Neither of these versions of course required a perforated spoon.

It was perfectly acceptable to drink an absinthe without sugar (une absinthe pure), but, based on all the historical evidence this certainly wasn't the norm, and there is no publicity material extant from any manufacturer that suggests this was the primary method - it's always referred to, if at all, as an alternative to the sugared version.

Occasionally absinthe was drunk diluted with other lower strength alcohol - white wine (une absinthe de minuit), or cognac (Toulouse Lautrec's speciality, un tremblement de terre). But these were very unusual methods, which always aroused special comment, usually disapproving.

Drinking neat absinthe (ie without water), certainly wasn't usual at any stage, and was never socially acceptable. Where it is referred to, it is always in the context of alcoholism and degradation - in the same way, for instance, as we might refer to someone drinking a neat triple gin today (the equivalent in alcohol content).

Today, modern absinthes are often marketed in conjunction with the so-called Bohemian absinthe ritual. This is not a traditional method, but a modern innovation developed less than 10 years ago, and inspired by the success of flaming sambuca and such like. A shot of absinthe is poured into a glass, and a teaspoonful of sugar is dipped into it. The alcohol soaked sugar is set alight and allowed to burn until it bubbles and caramelises. The spoon of melted sugar is then plunged into the absinthe and stirred in, which usually sets the absinthe itself alight. Ice water is then poured in, dousing the flames. This method, has become increasingly popular, especially since it was shown in the film "Moulin Rouge", but is a historical travesty, and would have horrified any Belle Epoque absintheur.