The joy of the espresso, gastronomy's magic bullet, is that it delivers the essence of the roasted coffee bean in all its subtle complexity without the slightest frill. No other liquid can match the sensual jolt it provides as it passes between the lips.
It is an agreeable struggle to judge how much of the drink one can consume in a day without spoiling the pleasure. Oscar Wilde never drank an espresso in his life but he understood the dilemma of the espresso connoisseur when describing why the cigarette is the perfect pleasure: "It is exquisite and it leaves one unsatisfied. What more could one want?"
The combination of a cigarette and an espresso is, I'm told, sublime. But the only enhancements to this elixir I know of are the smell and rustle of newsprint (chef Heston Blumenthal should investigate this pronto - there's a new dish in there).
This is why no day can be entirely satisfactory for me unless it begins with an espresso consumed with a freshly purchased newspaper. I have been known to walk miles to ensure the continuation of this ritual and avoid the disappointment of hotel coffee, usually served as an accompaniment to liven up the dullest meal of the day. I can think of nothing more dispiriting than being bludgeoned into a waking state by a bowlful of imitation Americano.
For me, espressos are essential if I'm to be productive. The late Hungarian number theorist and espresso-addict Paul Erdos once described mathematicians as machines that convert coffee into theorems. An exaggeration, of course, but we know what he meant. Espressos can also hinder creativity, reducing those who overindulge to fretful, unproductive, quivering wrecks.
How Voltaire managed to consume 50 cups of coffee a day yet still write so much is beyond me. His compatriot, the novelist Honore de Balzac, wrote about the dangers of imbibing too much caffeine in "The Pleasures and Pains of Coffee", where he mentions that the composer Gioachino Rossini, another coffee lover, had a series of overdosing binges, each followed by a period of cold turkey.
"Coffee is an affair of 10 or 20 days," Rossini remarked, "just about the right amount of time, fortunately, to write an opera."
It is only relatively recently that I came to love espressos. Like most English people born in the 1950s, tea was my hot drink of choice; coffee was seen as exotic. Every now and then, my mother would take a bottle of Camp Coffee from the back of the larder, pour out a sticky mixture of sugar, chicory and coffee and dilute it with near-boiling water. This produced a noxious brew, claimed by its makers to resemble a cup of coffee, and was surely one motivation for the 1968 Trade Descriptions Act.
When instant coffee granules arrived in the 1960s, advertisers conned us into believing that they tasted vaguely like coffee. In my undergraduate days, to offer friends a cup of Gold Blend marked one out as a slightly uppity connoisseur.
It was not until the mid-1970s that cafetieres brought something approximating to the authentic taste of coffee to the UK. As a graduate student beginner in Liverpool, I can remember being unable to face the prospect of spending three years wincing my way through cups of the instant stuff produced every morning by the departmental secretary.
A few colleagues and I set up a breakaway coffee club, aiming to put a pot of freshly-ground cafetiere coffee on the table of the refreshments area every day. Coached by the owner of a coffee stall in one of the city's markets, I began to appreciate the tastes of the different types of bean and the often overlooked, but crucially important, role of the roaster in the coffee-making process.
A few vacations in France taught me that it was possible to make even better coffee with more character and bite. But it was not until my first visit to Italy in September 1994 that I had an espresso epiphany and realised that all my preceding coffee-drinking experiences had been preparations for the real thing.
The revelation took place in Florence at the bar of a dark and smoky cafe off the Via Porta Rossa, where I felt like an alien. Why should I have to pay the cashier and then take it to barista? A bit odd, I thought, to be expected to drink coffee standing up and in less than two minutes. Could it really be true, as I'd been told, that it was illegal to leave the receipt behind?
But my discomfort disappeared as soon as I took in the powerful yet subtle aroma of the liquid and my top lip touched the slightly oily crema, resting on the surface like a luxuriantly smooth tiger-skin rug. Coffee, I saw for the first time, could be not only stimulating but also exciting.
I have since become an eager if inexpert observer of the barista's art. One day I shall overcome my incuriousness about technology and understand how espresso machines produce their little miracles by forcing hot water at high pressure through the compacted mass of 40-odd finely crushed beans.
For now, I'm content simply to watch the pre-warmed cup half-filled by the machine's issuant stream, often likened to the tail of a dark-brown mouse (it's more like that of a little rat, but for some reason that image has not caught on).
I had heard of the Italians' morning-coffee routine, but I didn't quite believe it until I had seen it for myself. They tend to slip into a cafe for an espresso, down it in a few gulps, return for another an hour or so later and then repeat the process. It is probably best to consume espresso within a minute or so of it being poured, but I prefer to linger over it, as the French do in their cafes.
But most Italians have no truck with such compromises. Once, when I worked in a Luxembourg office of the European Union, I noticed that the French barista left the cafe each lunchtime for about ten minutes.
During that time, an Italian took over and prepared espressos for people from his own country. The reason, I was told, was that the Italians complained to officials that the French could not make a decent cup of coffee and vice versa. So, to avoid unpleasantness, the French staff vacated their post every day so that the Italians could make their own. The Brits were content to get their coffee in a plastic cup from a wall-mounted machine.
Although the standard of coffee in Britain has improved in the past 20 years, it is regarded as distinctly odd to take it as seriously as wine. Not so in Italy, where I've often been reminded that the word "coffee" derives from the ancient Arabic "qahwat", meaning "wine of the bean". Moreover, a well-made espresso is a fine wine that is available to everyone. I have even heard that coffee bars in Naples collect small change to fund espressos for the destitute.
The availability of good espressos in Italy is extraordinary. A few years ago, during a hill-walk in a part of Sicily with scarcely a soul in sight, I wanted to conclude a glorious picnic with a restorative espresso. Sadly, I saw that the only sign of civilisation in the vicinity was a dark and dusty dive of a convenience store.
I need not have feared: the owner served me an espresso that would put quite a few three-Michelin-star restaurants to shame. A year later, at a conference held among the ruins of an industrial town several miles from Naples, the organisers set up a temporary espresso bar in a converted toolshed. Top-flight espressos were served all day long by a barista dressed in a bow tie and white dinner jacket.
To see how seriously espresso-making is taken in Italy, you would think it had been going on there for centuries, but no. The history is controversial but it seems that the espresso machine was invented around 1903 by Luigi Bezzera, an engineer in Milan and the owner of a manufacturing business who wanted to speed up the coffee-brewing process. The word "espresso" was well chosen, for it has three meanings appropriate for the drink - fast, pressed and by individual request.
Unable to turn his machine into a marketable commodity, Bezzera sold his patent to the industrialist Desidero Pavoni, who began to manufacture the forerunners of today's espresso machines in 1910. These machines produced espressos that were bitter and of variable quality. The crucial leap forward was made soon after the Second World War, when the high-pressure lever-operated machine was patented by Achille Gaggia. Modern espresso culture was born.
Dozens of variations on the basic drink emerged, all with Italian names, including the macchiato ("stained"), in which the espresso is wimpishly diluted with a little milk and foam, and the corretto ("corrected"), in which the liquid is pointlessly spiked with liquor.
I have a weakness for only one variation, the affogato ("drowned"), in which a bulb, or two, of vanilla ice cream is drenched with espresso. In the time required to consume it, the two components gradually combine to form a surprisingly tasty unity.
There is no doubt that the most popular variant is the cappuccino ("little hood"), at its best a glorious drink consisting of equal parts espresso, milk and foam. The experience of consuming a perfectly made cappuccino is sensual to the point of decadence.
Alas, the substance has been bowdlerised by Starbucks and other mass-market coffee companies, which have succeeded in replacing the drink - outside Italy, at least - with a frothy, insipid caricature.
If there were established crimes against taste, this replacement would deserve at least corporal punishment. Its purveyors should be condemned for the gastronomic felony of serving espresso-based drinks in paper cups, akin to the cruelty of asking someone to jive in a diving suit.
But it has to be admitted that Starbucks has led the way in making espressos available internationally, although it is a mystery to me why European entrepreneurs did not see the huge potential profit in marketing a high-volume, low-cost commodity much earlier. During its cleverly publicised relaunch last March, Starbucks recognised that the espresso is at the heart of its offerings.
It seems that the espresso is immutable, unimprovable. But the great chef Ferran Adria doesn't think so.
A decade ago, at the end of a glorious 30-course meal at his restaurant El Bulli on the Costa Brava coast, he asked me and my fellow diners whether we'd like an espresso to finish. Although it was gone midnight, we thought "what the hell", and were surprised a few minutes later when waiters delivered to us espresso cups that were upside down. I jumped in my seat when I turned over my cup and saw that it contained a frozen espresso.
It was a daring concoction, intriguing but not as satisfying as a first-rate espresso, the warmth and liquidity of which are essential to its appeal. Through an interpreter I suggested to Adria that this dish did not work; he demurred. But I took care to give him a compliment that I've never given anyone else, that he was a genius. He agreed.
I stand by my conviction that the espresso is, when well prepared, one modern culinary component that is impossible to better. Come to think of it, at around £1.30 a cup, it is probably the cheapest of all uplifting gastronomic treats, making it the ideal beverage for a recession.
Last year, Britons spent about £750 million on coffee, but only a small fraction of this on espressos. Think of the huge amount of money that would be saved if the majority of coffee-bar patrons switched to espressos from cappuccinos. The country's milk bill would fall and its carbon footprint would shrink too. Better yet, millions would appreciate the joy of savouring in a single shot Italy's greatest gift to the modern world.