The present can be altered and the future is yet to be shaped but one thing that is certain is that the past cannot be changed.
The events of history are what they are and no amount of discussion or argument will change that.
In the North we regularly run into problems over how that history is remembered, particularly over the way in which certain events are remembered and whether they are commemorated, celebrated or glorified.
Given our contested views of our recent - and not so recent - history, it is unsurprising that confrontations should arise over the more controversial events of the past.
How we look at our past tells us more about the present than the period being recalled.
Over the last week a new take on an old argument has sprung up over a republican commemoration in Tyrone. The row generated by this has less to do with the past but the way in which unionism regards itself today.
An unwillingness from some shades of unionism to accept the recent shifts in the political status quo, and in particular the presence of republicans at the heart of government, has led to an ultra defensive attitude where everything is viewed as a form of attack.
While such elements are on a defensive footing any attempts at progress are likely to be met with suspicion.
As is often the case however, those in other parts of the North could learn a valuable lesson from Derry where the Maiden City Festival, which ironically celebrates the epitome of unionist defensiveness, the Siege of Derry, is outward looking and will this year sit comfortably alongside the world’s biggest celebration of traditional Irish music and culture when Fleadh Cheoil na hÉireann comes to the city the following week.