The State Library of Victoria holds an engraving from 1865 titled ''Christmas in Australia''. About two dozen people, presumably an extended family, are having a Christmas picnic in what appears to be Ferntree Gully in Victoria.
At first glance, their Christmas is not too different from ours. Food, family, the outdoors; it looks lovely.
But the celebration depicted in the engraving would have been an enormous, expensive, time-consuming, and overwhelming logistical task.
Ferntree Gully is more than 30 kilometres from the Melbourne CBD, and in 1865 almost everybody lived in what we now think of as Melbourne's innermost suburbs — Richmond, lower Carlton, North and West Melbourne.
We can see three horses and in the distance a carriage. That wouldn't have been enough for 20 people. And carriages cost a lot of money.
The journey to Ferntree Gully would have taken hours along very poor dirt tracks. They would have had to bundle up everything: children, rugs, sporting equipment and pets. To say nothing of the food, which would have to be kept safe. (Well, maybe. This was before widespread understanding of the germ theory of disease.)
The journey probably started the day before. Hence the tent in the background.
When we think about how our lives differ from our ancestors, it's easy to focus on the big things: television, telephones, cars, and electricity.
That is, consumer comforts. The stuff that makes individual life less arduous.
But we forget how economic growth and technological change has made our relationships closer, easier, and cheaper to maintain.
A century and a half later, the classic Australian Christmas is no longer a trip to the bush but a suburban backyard barbecue. That change has only been possible thanks to the market economy and consumer society.
How? Let's take it one word at a time. Suburban, backyard, barbecue.
Obviously, Australia's sprawling suburbs rely on cheap ubiquitous motor transport. (Trains and trams can only service a few kilometres either side of their tracks). A short trip to the developing world should be enough to demonstrate that car ownership indicates wealth.
Backyards, too, are a sign of prosperity.
As the food historian Barbara Santich points out, it was relatively recently — that is, after the Second World War — that backyards were turned over from home food production and gardening to leisure. The reason was affluence, as well as the convenience and availability of supermarkets.
Hence, the 1865 journey to Ferntree Gully. The Australian backyard of our ancestors was an economic asset, not a social setting.
This remained the case well into the twentieth century. A short book from 1928 explains to Britons the difference between Christmas in Australia and in the mother country. The book tells the story of the "long trek" taken by Australians on Christmas Eve to the mountains and the sea. Cars would be heavy loaded with tent-poles and gramophones and food. And, of course, spare tyres. Celebration would start at dawn the next day.
Finally, the barbecue. The barbecue is a remarkably recent invention. Its pre-war equivalent was the "chop picnic", where meat was cooked on a small fire in the ground. The figures in the background of ''Christmas in Australia'' are probably having a chop picnic.
When backyards were freed up, Australians started building permanent barbecues out of brick fuelled by firewood. (Nobody wants an open fire in their backyard.)
The free standing portable metal barbecue fuelled by a gas bottle became prominent in the 1970s. Gas barbecues are better in almost every way: they're cleaner, heat faster, and, as they cool down rapidly, they're safer too. It was only thanks to better materials, cheaper energy and technological innovation that the free standing gas barbecue became the Australian norm.
So our traditions change according to our prosperity. Our relationships do too.
That family in Ferntree Gully 150 years ago were — as European settlers — at least a four-month journey on an iron clipper ship away from the family they may have left behind. Communicating with their relatives by letter would have taken twice that.
In the 1930s the situation was much better. An Australian wanting to travel to Europe could have flown. But aviation was in its infancy. The flight would have been extremely high cost — far too high for a mere holiday — and taken more than a week.
Today we can cross the planet in 24 hours. And, with the internet, communication is instantaneous. That technological change has made seeing and appreciating our family much cheaper.
The cost of sending a gift to a family-member across the other side of the world by sea freight has declined by two thirds between the 1930s and 2013.
Flights to see family members are a tenth of what they were.
An international phone call is one 100th of what it was 85 years ago. If we use Skype, it is effectively zero-price. Letters, too, cost nothing online.
Australia is a very rich country — one of the richest in human history.
And there's no better time to reflect on how that wealth has made it easier to have stronger relationships than Christmas.