We are now witnessing events that at one time, not so long ago, would have seemed impossible. The first state visit to the UK by an Irish president is another step in the normalisation of relationships between the two countries who share such an intimate, if tortured, history. Of course, such a visit was inevitable following the Queen's visit to Dublin, which really broke the mould and created history.
But the truly astonishing event tomorrow is the attendance of former IRA commander and now deputy First Minister Martin McGuinness at a state banquet at Windsor Castle.
His party could not bring itself to be part of the historic events in Dublin, but it recognised that the relationships between the two countries had changed irrevocably and that it should be part of that change.
Mr McGuinness, to his credit, shook hands with the Queen during a subsequent visit to Belfast and he has been the main member of Sinn Fein to signal changes in attitude, whether to politics or the security situation. Remember his denouncement of dissident republican killers as traitors? That has made him a hate figure among some extreme republicans – undoubtedly some of them his former paramilitary comrades – but he has shown the courage to demonstrate what leadership is all about.
To an outsider it can seem that the peace process is trundling along at a glacial speed, if at all.
They might wonder why it has taken the UK and Ireland so long to act as friendly and long-standing neighbours. But events like the state visit over the next few days are part of a healing process. Only the extremes will criticise it or the participants.
And there are other rifts which are still apparent; for example, between the First and Deputy First Ministers. Perhaps, as they sit down to dinner tomorrow night, they might reflect that their personal spat is miniscule in comparison to the historic enmity between the UK and Ireland.
If that can be repaired, then surely they can work together constructively to cement the peace process in the province.