There is a species of well-known quotes that fulfils such a useful function that it's convenient to overlook whether or not they were actually said. Although there is no official record of it, Harold Macmillan is often cited as saying: "Events, dear boy, events," apparently in response to a question about what blows governments off course.
Well, obviously it's events - non-events are unlikely to do it. But the meaning taken from the quote is unpredictable events or those one can do nothing to prevent. They are the kind that really knock you sideways.
And the same goes for football, or indeed any sport. On December 17, Mauricio Pochettino was one of the most admired and sought-after coaches in European football. His team, Tottenham Hotspur, were third in the Premier League after playing 17 matches, having gained 39 points, six points behind Liverpool, who had set a phenomenal pace. More significantly, perhaps, Spurs were 13 points ahead of Manchester United, a team with enormously larger resources and one of the most successful coaches of the modern era, José Mourinho.
And then something happened that changed the fortunes of both teams. Mourinho was sacked and Pochettino was named - at least by the bookies - as the favourite to replace him, probably at the end of the season. This did four things. It put extra pressure on Pochettino, who was placed in the position of denying he wanted the job, something he signally failed to do.
It put extra pressure on the Spurs team, who didn't know if their manager was going to stick around, and were inadvertently placed in the position of playing to keep him. It relieved the pressure from the United team, who had been paralysed by Mourinho's egomania, And finally it meant that the United caretaker, Ole Gunnar Solskjær, had nothing to lose.
Three months on and Spurs are still in third place. Just. But United have closed the gap between the two teams to just three points. The joke doing the rounds is that Spurs are going to finish fifth in a three-horse race.
The first thing to say is that Pochettino remains a first-rate coach. Over the past five years, he has regularly outperformed managers of teams with much more player-buying and -keeping power. And he has also had to contend with difficult circumstances, not least the fact that Spurs have played their 'home' games for the last two seasons at Wembley, as their new stadium has been built and its opening delayed. He has also guided Tottenham to the quarter-finals of this season's Champions League.
But he has undoubtedly suffered in the league since Mourinho was sacked. For a start, his luck changed. Spurs lost at home to United in January in a match they should have won by several goals, and in which his super-striker Harry Kane was injured. Next he lost Dele Alli to injury.
Yet remarkably, shorn of their two leading stars, the team went on a winning spree. You could put that down to Pochettino's motivational skills. But the success led him to make several big mistakes. The first was to announce before a match at Burnley that his team were going for the title and the game would be a test of how serious they were. Why heap needless pressure on a side in third place?
The second mistake was to name the returning Kane in the starting XI. While the England captain had been away, Son Heung min had been playing so well that the South Korean was being mentioned as a potential Player of the Year. But Kane was eager to start and, given his significance to Tottenham, the fact that he is coveted by every major team and is not paid nearly as well as players at the wealthiest clubs, you can understand Pochettino's desire to keep his leading goalscorer happy.
A rusty Kane is still a goalscorer - just not as ruthless a finisher as he is when fully fit. Kane duly scored against Burnley but the team looked slow and predictable, and Burnley won. That's when Pochettino made his third big mistake. Normally respectful of referees, he walked on to the pitch to shout at Mike Dean, got himself a two-match touchline ban and looked very much like a manager who had cracked.
He then made his fourth mistake by declaring that it might take another five years or more to instil a title-winning mentality in his team. Perhaps, but they didn't have five years because they were playing Chelsea in midweek, and they duly lost. Spurs then scraped a draw against Arsenal in a game they should have lost, before losing at lowly Southampton .
No one is talking about Pochettino going to United any longer - which is one silver lining for Spurs fans. He's not the first manager to suffer from the interests of another club. Marco Silva's fine start at Watford last season came unstuck when Everton began courting him. And managerial uncertainty seldom improves performances - Manchester United swiftly declined when Alex Ferguson prematurely announced a retirement in 2001 that he ended up not taking.
Yet Pochettino has tried to exploit the situation by saying that it's good to be the subject of attention - it shows you're doing well - without in the process being able to use it to his team's advantage. It's not as if United's interest gave him an effective bargaining chip with Tottenham's chief executive, Daniel Levy: Spurs did not buy any players during the January transfer window. And in the 13 matches since Mourinho was sacked Spurs have assembled only 22 points.
It is hard to imagine Ferguson, or Arsène Wenger in his prime, allowing themselves to be dragged into a media-run job audition for another club. Pochettino is smart enough to learn from the experience.
With the Champions League quarter-final against in-form Manchester City, it would be a massive upset if Spurs proceeded any further in the competition. And with away games to City and Liverpool in the Premier League, they now have a battle on their hands to remain in the top four.
Another quote attributed to a politician - this time Teddy Roosevelt - is: "Speak softly and carry a big stick." At his best, Pochettino has been a model of humility with a fierce but understated competitive streak. It has served him well until now, before he began publicly challenging his team and losing his rag with referees.
If he's going to guide his team to a top-four slot, the Argentinian needs to forget other clubs, lower his profile and raise Tottenham's game.