That empire is gone but we still think colonially. And that makes us vulnerable to the needs and ambitions of foreign market forces.
Three decades ago, New Zealand wool was a major export. But the advent of synthetic fibres in carpet manufacture - carpets made from coke bottles - dried up that market.
According to government data, from 1982 to 2011, New Zealand's sheep population declined from 70.2 million to 31.1 million. Farmers first converted to sheep meat products and, as that slowed, many sheep pastures were converted to dairy farms.
We are still the world's second largest dairy exporter. But how long do you think that will last?
As China grows richer, it seems an opportunity for our export market in dairy. But if the Chinese do what they have done in other areas, we may have to rethink our future.
The Chinese are interested in stability and control of commodities worldwide. They've already bought the Crafar farms. Why stop there?
Vulnerability to world forces isn't limited to New Zealand. Right now oil prices are falling and it's not due entirely to decreased demand - although that may be a factor if Angela Merkel's austerity chickens come home to roost in a recurrent European Union recession. No - the fall in oil prices owes much to the rise in United States production.
The US Energy Department data shows that US production peaked in 1970 at 10 million barrels daily, dropped to 3 million by 2003 - making the US dependent on Mid-East oil - and has risen since 2012 to an expected 11 billion barrels in 2015 from shale production.
It thus threatens Russian oil and gas revenue and Russia's influence over Europe. If President Barack Obama, pandering to his neo-con right, chose to seriously damage the Russian economy - dependent as it is on energy export - in return for Vladimir Putin's aggressive response over what the Russian perceives as a Nato threat on his borders, that damage could be done by stroke of a pen ordering an increase in US production of oil.
The future of this country is imperilled by its continuing colonialist thinking and its consequent over-dependence on commodity export.
The future of Whanganui cannot rest on the shaky whims of commodity export. We are small enough to be flexible in our thinking and have the assets and potential to be the vanguard of a new approach to prosperity.
We are an educated population and, if we want to prosper in a manner consistent with our cultural history, it can come through production of intellectual property. Here we have high-speed internet - a bunch of people with a few computers and 3-D printers could be making the Next Big Thing right here in Whanganui.
We can then change our city motto from its implied out-of-the-way location and invited transient visit to the more elegant and simple one of "Whanganui Makes - The World Takes".
Jay Kuten is an American-trained forensic psychiatrist who emigrated to New Zealand for the fly fishing. He spent 40 years comforting the afflicted and intends to spend the rest afflicting the comfortable.