For someone who has spent most of his adult life trying to abolish it, the border has been very good to Thomas 'Slab' Murphy.
Because his farm straddles the frontier separating Northern Ireland from the Republic, he has been able to exploit the anomalies of the invisible line that runs through his property.
At times when the Army and police raided his home, Murphy was able to cross into another part of the property that happened to be in the Republic and out of the security forces' reach.
More crucially, the anomalies between tax regimes and the ease of sending livestock, 'washed' diesel, untaxed cigarettes and illicit alcohol, have profited 'Slab' for decades. The criminal mini-empire he established also funded the Provisional IRA's war-chest.
As a result of the region becoming a virtual no-go zone for normal policing during the Troubles, an entire smuggling industry has embedded itself along this section of the border.
It has also helped solidify a cult of 'Omerta', which means that no one living in the epicentre of this empire dares speak out, or collaborate with the authorities. What was under attack, therefore, when Operation Loft was launched last week, involving 300 Garda and PSNI officers, as well as the Republic's Criminal Assets Bureau and Her Majesty's Revenue and Customs, was this Omerta itself.
This latest sortie on south Armagh Omerta is directly related to the murder in the nearby Cooley peninsula of Garda Adrian Donohoe.
The garda's suspected killers are a south Armagh-based crime-gang with deep familial roots in the region, as well as connections to republican veterans from the area.
Since the Donohoe murder, gardai have come up against the seemingly impenetrable wall of silence that this local Omerta has constructed.
Garda sources are not confident that even a major cross-border operation against the smuggling empires in south Armagh/north Louth will create cracks in this wall; the cult of Omerta being so immersed in the culture of the region to make that breakthrough nigh- impossible.
Any assault on the profits of these enterprises will inevitably impact on the fundraising activities of those republicans who refuse to buy into the peace process and continue to prosecute that 'war' to erase the invisible line that cuts through 'Slab' Murphy's land.
Like their predecessors, groups like the New IRA finance their war 'materiel' and foot-soldiers through the proceeds of smuggling and other activities, including robbery and extortion.
In this world, pragmatism (rather than ideology) is the order of the day.
Some southern newspapers have erroneously reported that 'Slab' Murphy has broken with his old comrades in Sinn Fein, but veteran Provo-watchers in the Republic's security services see no evidence of this. Murphy (60), who was named under privilege during the Smithwick Tribunal as a former chief-of-staff of the IRA, remained behind the Sinn Fein/Provisionals leadership, even after the Real IRA was formed in 1997.
The point here is that, while some of Murphy's former comrades in south Armagh/north Louth have long since parted from the Provisionals, they co-operate, rather than compete, when it comes to the business of keeping the cash flowing from the region's covert, illicit industries.
The boundaries between peace-process republicans and dissident republicans are far more blurred, compared to the sharp, bitter antagonisms between them in Belfast, or in Londonderry.
Down in a region where police patrols can be driven out of villages by armed shows of strength (witness the PSNI's humiliation in Meigh a few years ago), business is business – regardless of which side of the latest republican divide you are on.
That much is certain, along with the stolid permanence of Omerta, which is, once again, being tested by both states on this island.