In the summer of 2019, Celtic reached a fork in the road. Kieran Tierney, a die-hard fan of the club, never sought to move away from Parkhead. When Arsenal hinted they would be willing to pay £25m for his signature, pragmatism was always going to win out.
To prepare for the inevitable, the club shelled out £3 million to bring in Boli Bolingoli from Rapid Vienna. Once Tierney's move to north London was confirmed, around £2.2m was spent to sign Greg Taylor from Kilmarnock.
Both players' respective contributions to the cause proved to be a salutary lesson in the danger of being seduced by exotic continental club names.
Bolingoli, a man with an unfortunate penchant for jewellery, was happy to go out to dinner knowing his cousin was Romelu Lukaku.
After an uncertain start to life on the park, his questionable character was exposed when he broke Covid-19 quarantine rules by making an unsolicited trip to Spain and then playing Kilmarnock at Rugby Park on his return.
After being loaned to Istanbul Basaksehir, he played a couple of games at the start of the following season before moving to Mechelen on a free transfer.
Taylor, above, will be replaced as Celtic's first-choice left-back by Kieran Tierney.
Arsenal star Tierney looks set to make sensational return to Parkhead
Brendan Rodgers was angry that fans chanted Tierney's name while Taylor was on the pitch.
Taylor, in stark contrast, did what she had always done. He was initially second choice behind Bolingoli, he bided his time, worked hard, made no fuss and took advantage of the opportunity when it arose.
Having overcome a challenge to his position, he faced the others. Diego Laxalt, Jonny Hayes and Alexandro Bernabéi.
When Ange Postecoglou replaced Neil Lennon as coach in 2021, Taylor, then 24, was thrown another curveball. Could he adapt his game to the Australian one and play as an inverted winger? After a necessary period of adaptation, the answer was a resounding yes.
As Celtic re-established their dominance in Scottish football, the Scot grew in stature. He is no longer just a survivor, but an integral part of the side.
As the team evolved, so did Taylor's role within it. Along with Callum McGregor, Joe Hart, Alistair Johnston and Cameron Carter-Vickers, he seamlessly became a valuable part of their leadership group.
But the Gourock man did not earn the trust of a succession of managers simply by being a good influence on others. You don't survive five seasons in a row out of six at Celtic and win 10 major honors unless you deliver consistently on the park.
While replacing Tierney, a generational talent, was always the definition of mission impossible, Taylor has been an excellent signing for the club by any measure.
Now 27, he is entitled to see his service and status reflected in the terms Celtic offer him in any new contract that comes forward.
Taylor (left) and Tierney have worked together in Scotland during their careers.
Fans are excited at the prospect of fan favorite Tierney returning to the club.
But Taylor has been an excellent servant in his absence and, unlike Tierney, is rarely injured.
Although he is now free to talk to other clubs, he wants to stay at Parkhead. Brendan Rodgers certainly wants to keep him.
But if a deal cannot be reached, the Scotland international will surely have no shortage of good offers from elsewhere.
Taylor deserved better than to hear Tierney's name chanted by a section of the crowd towards the end of Sunday's routine victory over St Mirren.
While the return to Parkhead for the Arsenal man carries obvious emotional appeal to the grassroots, you can understand why Rodgers was so upset about him expressing himself while Taylor was on the pitch.
“That is a total lack of respect,” said the manager.
'Greg Taylor, he has been absolutely incredible at this club. How do you feel? He almost broke his nose there, bleeding for the club, for a cause.
'It's not very respectful. You sing for another player, no matter what Kieran's story is. I don't like that.'
It was a short end to what was otherwise another good day for Celtic as they opened the gap on Rangers to 13 points.
Taylor in action for Celtic against St Mirren in Sunday's 3-0 win for the champions
Tierney has the ball for Arsenal, but his appearances have been very limited
Taylor and Tierney during training in Scotland with Kenny McLean and Callum McGregor
Rodgers, naturally, didn't take any media questions about Tierney. That will remain the case until a pre-contract agreement is confirmed for the player to return in the summer. Only then will Celtic see if Arsenal are willing to allow him to return to Glasgow this month.
While Tierney's return would be a hugely popular move among the Celtic support, it would also carry a degree of risk.
Since moving south, he has suffered a shoulder injury, a groin problem, three separate hamstring injuries and an abductor problem.
Stretched out against Switzerland at the Euros while playing for Scotland, he has played a total of 69 minutes of football for his club this season and has missed 94 games for club and county since leaving Celtic.
No one is sure if he has simply been unlucky or if the number of absences is the same as his 27-year-old body.
But expecting Tierney to play 50 games a season for Celtic when he never managed 40 in a spell for Arsenal seems a bit fanciful.
This explains why Rodgers was so keen to put a protective arm around Taylor after Sunday's game.
Having missed only eight games since joining the club, his availability has been notable for a combative full-back. And with Celtic playing between 50 and 60 games next season, that reliability would be very welcome.
The question is not whether Rodgers could give both left-backs enough minutes to keep them satisfied. He can. It's a question of whether the pocket threads would stretch enough.
Although Tierney's days of earning six figures a week in the English Premier League are clearly coming to an end, he will still command a significant salary. Taylor will also want to secure his future with the biggest contract of his career as he approaches his peak years.
While the financial burden may be offset by Bernabei's imminent £5m transfer to Brazilian club Internacional – plus Alex Valle's return to parent club Barcelona in the summer – the cost of Celtic keeping two senior internationals in the books for a defensive position can still be prohibitive.
However, from a purely sporting perspective, Rodgers would like to see that happen.
Having had the unenviable task of filling Tierney's shoes for so long, Taylor may soon share the stage with him. Having stayed the course and seen so many competitors for his position fall by the wayside, he earned that honor.