The human population has greatly increased in most parts of the planet. Inevitably there has been movement. Looking at much of this and the longer past at the thinking and hopes of those on the move, one idea comes to mind and that is in all the discussion we do not take full account of what I call "The Eldorado Effect".
The story of this has a long article in Wikipedia. Essentially, it means the legend and search for gold and riches in faraway places that have inspired or motivated chiefly men to go and seek it out to transform their lives and either their families or groupings.
Great Great Grandfather was affected in 1848 when sailing into New Orleans with his ordinary commercial cargo and finding the harbour full. It was because the ships could not get out, their crews having deserted to go to the gold fields.
Most of his own crew did and it was only because he had the cash to recruit the few wanting to return to Britain that he made it home. It was his last voyage. Having survived thirty years at sea since the age of 12 he had a small property portfolio in public houses.
He was able to retire and leave the rest of them to it. It meant that he was a lot better off than the vast majority who went to seek the gold and silver. He lived another thirty years to enjoy it. Most of prospectors died young and hungry.
The El Dorado that is Europe to many parts of the world offers the reverse incentives. There may not be any gold or silver but there is the prospect of being fed, housed and cared for in a way and on a scale that is beyond their expectations in their place of origin.
But the effect can exist within Europe. There has been comment on the numbers given for British now living in Europe. Yet it is not an even spread, nearly half of them being in Spain.
They were drawn there in the past mostly by ideas that the property boom would make them rich or the cost of living make their money go a lot further or that the sun would make living more easy.
Similarly, the same ideas apply to some of those who went to France in particular the areas more to the South. As in Spain a great many have been disappointed and others in the UK, in the same way as Great Great Grandfather did a lot better at home.
Quite how many people a year cross national boundaries is a matter of hot debate. There are many variables, the exact data is hard to find and many are not recorded. But if it is one per cent of world population, this could be around seventy million and half that thirty five. Even one tenth of one per cent amounts to seven million.
It is very unlikely that the distribution will be even or that in general inflows and outflows will be matching. There will be plus ones and minus ones and at either end extremes of inflow and outflow in terms of numbers. Given the rise in world population as a whole this was predictable in terms of past migration across the globe.
During much of the 19th Century and into the 20th in the UK there was real concern about over population. In the 1860's, with a total for the Atlantic Isles of 26 million plus, given the poverty, disease and overcrowding in the urban centres there were national emigration societies to assist emigrants to the colonies.
There was the real fear that increasing numbers would mean The Atlantic Isles being unable to feed itself and then food import costs causing the Balance of Trade to go into permanent deficit, if the food was available. If it was not then starvation beckoned.
For those in the slums or condemned to harsh poverty the simple life of a small farmer in a colony or similar would seem to be almost an El Dorado compared to a short life in the rookeries of London, Liverpool or Manchester.
Given the gold strikes and such like and other opportunities many places in the world did seem to be almost if not El Dorado's and many did not need much encouragement to go, only the cost of a steerage berth. So they went and in large numbers.
The USA is largely the product of The Eldorado Effect of the past. The American Dream was an extension of this and it is still a powerful force for many in the world to try their luck either as legal or illegal migrants. The reality, however, is becoming very different and for very many will be a harsher experience.
The world has changed and now we have the notion that inward migration is necessarily good. Some of it might well be. Stripping the undeveloped world of its doctors and nurses has been keeping the NHS in the UK afloat for a little time now. But there are doubts about just how many is good.
Clearly, The Atlantic Isles can no longer feed itself, so equally clearly the cost of imports has to be covered. Sadly this is now probably impossible in terms of the Balance of Trade and we are now reliant on financial profiteering and borrowing. This might not last despite our leaders saying it must.
There is no doubt about the relative attractions of the UK for many people elsewhere. Many were already on the move here by the early 1990's. So when the Labour Party went around the world to welcome all they were adding an El Dorado effect for movement to the UK.
We have been here before as this wonderful lyric, "Mountains of Mourne" by Percy French in 1896 suggests. Scroll down for the words. Great Great Grandfather, above, had an eldest son, my Great Grandfather who married a girl from a Kilkeel family in the shadow of the Mournes.
As a small child, I remember meeting her youngest brother. He gave me a sip of his port. Thirty years later driving down the valley of the Douro with my camping trailer it was tempting to stay for good.