We can easily forget that the economy is a miracle. So it pays, whenever we're in need of rejuvenation to follow the example of the great economists in unravelling the mind-boggling complexity of even the simplest economic transactions. Here's a little story from my own life which helps me to remember my sense of wonderment at this thing called The Economy and my commitment to the practice of economic science.

I'm sitting in a café with a laptop, watching my university walking past and admiring the spectacular view. On the table in front of me sits a flat white. Coffee. I need it pretty badly these days to function. An Australian should really prefer tea I suppose, especially one with my British heritage and All That, but it's now part of my morning routine. And my mental triage routine. Whenever something goes bad, whenever my mind seizes up, really if I just need a moment to myself (which is often), I'll go get myself a coffee and watch people.

As I muse upon the elixir in front of me I'm struck by a thought. I'm often intrigued by little questions that pop into my head, make a little note of them and set them aside for later, but this one seems important to answer right now. So I beckon over my Japanese friend who's working here in Brisbane while she studies English.

"Eri, weird request" I begin, "but can you answer me three things? First, what brand of milk do you guys use? Second, what kind of coffee beans? Third, what brand is your espresso machine?"

It's a little difficult to find out, because she herself never thinks that deeply about where the milk, the beans and the machine come from. Why would she? She doesn't have to. But the milk turns out to be Dairy Choice, the coffee beans are Toby's Estate, and the machine is a La Marzocco. Excellent. I grab my laptop and stride downstairs to my desk where the internet awaits.

A little further poking around reveals that Dairy Choice is a company headquartered at the Docklands in Melbourne, in the State of Victoria about three thousand kilometres to the south which acts as a middle man between Australian dairy farmers and retailers. I have no idea who the farmer was that made the milk, and it's hard for me even to contact the company, but why would I even want to?

Toby's Estate is a company which makes a point of making their story readily available to the slightly crazed world that consists of coffee connoisseurs in Australia. Toby Smith started life as a lawyer, but left that life to work on a coffee plantation in Brazil. Coming back to Sydney he built up the company which now brings the coffee beans which went into my flat white to Australia all the way from Toby's (literal) Estate in Finca Santa Teresa in the Chiriquí Province of Panama.

La Marzocco similarly make a point of making their story readily available. To my delight (and that of Julia Ferrari somewhere "up there" watching over her great-grandson) I learn that the machine my coffee was made on was hand-made in Florence, Italy, not too far removed (by Australian standards), from the lands of my other ancestors in the north of Italy. Once assembled, the machines are shipped across the world to Melbourne, and spare parts to Sydney for distribution in Australia.

So, the three basic inputs of my flat white alone came from three different countries on three different continents on literally opposite sides of the globe. Tracking down their origins led me immediately to Australian farms (often in fertile Victoria), a Panamanian plantation, and a workshop in Italy. The chap who combined them together to produce the final product (and the whole university hold him to be a master of his art) is of Ukrainian extraction, of all places.

How did they get here? Our Ukrainian barista likely as not arrived here on a Boeing (headquartered in Seattle, in the United States of America), or an Airbus (headquartered in Toulouse, France) aircraft so complex it's quite difficult to track down the parts which comprise them, let alone their origin, but which seem to number on the order of several millions. The materials he was working with likely as not arrived in Australia on freight aircraft built by those companies, or on sea freighters operated by one of the global shipping firms, (one of the largest being Moller-Maersk of Denmark), built in massive shipyards, (one of the largest being the Hyundai Heavy Industries Ulsan Shipyard in South Korea). Quite possibly, my flat white has now required the input of a Ukrainian, some tens of Panamanians, some hundreds of Italians and Australians, some several thousand Americans, French, Danes and South Koreans and the use of objects numbering somewhere in the tens of millions.

This isn't even thinking of the freight companies in Australia, the dockyards, the air-and-sea traffic controllers, the logisticians, the accountants, the lawyers…

How is this possible? I'm left with the conclusion that it is impossible for any one person on the planet to make my single flat white. Certainly I couldn't. I don't even know how to froth milk, though I could walk over the campus to talk to some colleagues in the School of Food Science who have studied the optimal method extensively.

The people who work at our café don't know when I'm going to come to get my coffee either, as you might have guessed; it's pretty unpredictable even for me. They don't know when any of us are going to come. Not for sure anyway. And yet they draw on the output of all these people from all around the world just so to have the ingredients and machinery on hand such that they can have that cup on the table in front of me within two minutes.

Literally thousands of people, millions even, cooperated to put that coffee onto the table in front of me, and I take it for granted that whenever I come up here it'll be waiting for me. Literally thousands of people, millions even, all across the globe, people who've never met each other and probably never will. People who would, given our human nature, quite possibly hate each other if they were ever to meet.

It took all these people working together without knowing it. It took James Watt's invention of an efficient steam engine two hundred and fifty years ago in a tiny workshop in Scotland. It took the development of the internal combustion engine. It took Alexander Graham Bell's invention of telecommunications. It took Sir Tim Berners-Lee's development of the internet. It took the negotiation of some hundreds of governments over decades to allow trade across their borders. It took the invention of rule of law and the institution of private property over thousands of years. All to bring me this little cup of coffee.

It's a miracle. Utterly mind boggling. And I take it for granted. You probably do too.

Not to take it for granted would just take up too much time which could be used for thinking about things we can't take for granted. Love, health, hapiness.

How is this possible? This is a cup of coffee! Not even the espresso machine it was made using. It's not even the laptop computer I'm writing on. It's still less the bus I came to the university on. It's even still less the monumental two hundred metre high office tower I just left my mates at the Queensland State Treasury at (after, yes, morning coffee). How do we have the material necessities, the goods and the services, which allow us to go about what Alfred Marshall called "the ordinary business of life"?

How is the miracle that is the economy made reality? To be more specific: what is an economy, how does it function? How is it that the material necessities of life are made available by such a vastly complex system which, on the whole, functions so well we rarely have to think about it?

Those are the questions economics seeks to answer. That is why economics is so enthralling, that is why it's so important, that is why we keep studying it.