Good relationships between neighbours turn on allowing each other respectful space while allowing for accommodation when needed. Sounds simple enough in theory: but the trials and tests of 800 years of shared history between Britain and Ireland suggest we should take nothing for granted.
This week the Brexit talks begin in earnest. Britain's exit from the EU was always going to be more challenging for this country than any other in the EU.
Closer ties between the UK and ourselves meant that London was a most valuable ally in fighting our corner on mutual interests in recent years.
We are now on divergent paths, but the ties that have been so transformative over the past few decades will survive whatever stresses lie ahead.
With Brexit, some conflict along the way is inevitable. But as today's visit of Prince William and his wife Kate shows, we should always have more in common than we do apart.
It was the co-operation forged first through John Major, and then Tony Blair that lead to the Good Friday Agreement; resulting in a new age of mutual benefit between our islands.
As former US president Bill Clinton put it back in 1998: "The path to peace is never easy. They have chosen hope over hate, the promise of the future over the poison of the past."
It was this promise of the future and the spirit and kinship which was so exemplified in the visit of Queen Elizabeth in 2011.
It reminded us that while branches may grow in different directions many of our roots are the same.
While some would seek to emphasise differences, it can't allow any distraction from the enormous strides that we have made together.
These advances were best reflected in the words of the queen when she spoke in Dublin.
At the time she expressed: "sincere thoughts and deep sympathy" for the victims of the Troubles on both sides.
The sincerity of those words was acknowledged at the time by Gerry Adams, who commented: "I believe that her expression of sincere sympathy for those who have suffered as a consequence of our troubled past is genuine."
Prince William and Kate come here in a similar demonstration of normality and closeness.
Everything evolves and changes and the same applies to relationships.
With so much at stake and in the melting pot, it is vital to recall we will still be neighbours long after the dust has settled on any potential trade agreements.
That is why the arrivals of the royal couple at such a time is to be welcomed and appreciated.
In his seminal work 'Translations', Brian Friel struggled to bring context to our separate identities. He wrote of a "syntax of opulent tomorrows".
This was as he outlined a response to "mud cabins and a diet of potatoes". And so it was.
But as he also affirmed it provided for the possibility of harmony through the accommodation of difference.