It’s often said that trust is hard to win but easy to lose.
A relationship that has taken years to strengthen can be irrevocably destroyed in an instant.
Reputations are the same.
People spend lifetimes building a status that could see them remembered for all time, until they bring it crashing down.
An extreme example perhaps, but Maurice Johnston is a case in point.
Once a fans’ favourite, a very successful striker (including a memorable goal to help win the league in 1986) until, of course, events in 1989.
More recently, consider the case of Brendan Rodgers.
The man who was here for the Ten, feted by fans and spoken of as one of the greatest managers in the club’s history.
Until, one day, he wasn’t any more.
The examples are not going to end there, not if this season continues in the current manner.
Celtic Park is now akin to a bonfire, and the reputations of so many people – hard won across many years – are going into the flames.
Players, a manager, board members; all of them face the real prospect of the past decade and their achievements being wiped out and forgotten.
And it’s hard to blame this on anything other than vanity.
Too many people who see themselves as being more important than the club, who cling to some strange notion that they can somehow turn this around, in spite of all contrary evidence.
There is certainly anger, not helped by events in wider society where people are frustrated at limitations on their normal lives.
But that’s not Celtic’s real problem; instead, it’s apathy.
Most Celtic fans of my acquaintance increasingly find this season irrelevant or amusing.
There is simply no belief that we might show even the hint of improvement.
This is not about defeat; winning Ten was always a huge challenge, which is why it’s not been done before.
Teams that were amongst the greatest in Celtic’s history tried and failed.
A financially doped Rangers team with every advantage also tried and failed.
Everyone loses eventually; what is causing anger is the meek manner of our capitulation.
When Celtic stopped Rangers winning Ten-in-a-row in 1998, it went down to the very last day.
Indeed it wasn’t clear that Celtic would do it until the last 20 minutes of the season.
This current Celtic side have offered as tame a league surrender as has been seen in my lifetime.
The 1990s was a low time, and saw worse Celtic teams than this fail to challenge.
But in those cases, you knew this was a poor team, put together on hugely inferior budgets compared with Ibrox.
This Celtic team however is far and away the most expensive in the country.
Even the summer saw big transfer fees and huge wages splashed around.
Realistically, the challenge was probably over at Christmas.
But now with four months to go it is well and truly done.
The name Rangers will again be etched on the league trophy, although if it’s not the same club.
Neil Lennon is clearly not going to be Celtic manager next season; there is literally more chance of my being offered the job.
For a while my view was that it might be best for him to stay, as long as he understood this and work was ongoing to replace him and plan ahead.
That can no longer be the case.
But this team’s descent into the abyss is destroying his reputation, to an extent that even years (forgiving though they can sometimes be) may not fully restore it.
And it is not simply him who should worry; many others at Celtic Park face the same fate, unless something is done to relieve the tension and begin to change this poisonous atmosphere.
The last time St Mirren beat Celtic was in 2010; it also saw the end of a Celtic manager’s time in charge (Tony Mowbray).
Today, history needs to repeat itself.
And that means today.
Matthew Marr is a Celtic fan and regular contributor to the site. He is originally from Dundee.