The aggression of Hibernian was the focus of much of the post-match comment but strength comes in other forms on the football pitch and delayed reflection on events at Easter Road may provide more substantial truths than the undeniable assertion that Pat Fenlon's side were, in football parlance, "up for it" on Saturday.
The severity of the challenges by Hibs players was condemned by Neil Lennon, the Celtic manager, and defended by Fenlon.
Owain Tudur Jones, the Hibs defensive midfielder, was succinct in his assessment: "If it was the other way round and Celtic were playing Barcelona and had to get in their faces and get tackles in Lennon would be a very happy man. So it is a little bit of kidology really. It showed we were well up for the game. I do not think there were any ridiculous tackles - big, lunging two-footed tackles - there was none of that."
Referee Calum Murray, who was lenient throughout to the ire of both sets of fans, booked Ryan McGivern and Liam Craig. Michael Nelson was fortunate to escape official censure but the lessons of the match extend further than how players instinctively play to a referee.
The matter of strength was the constant. It was manifested in a Hibs side that has been consistently criticised as a "soft touch" but who played with a passion that did not exclude strategy and technique. Fenlon could congratulate his goalkeeper, Ben Williams, on excellent saves from Teemu Pukki, Anthony Stokes, Georgios Samaras and James Forrest. But there was much more to Hibs than any rearguard desperation. They played with commitment throughout, and with composure and purpose on occasion.
Paul Heffernan's major contribution was to score from an offside position but the controversy over his goal should not obscure a consistent display of guile and movement. The Irishman is a skilful, clever player who should prove to be an influential acquisition by Fenlon.
With Kevin Thomson excellent in midfield and Craig industrious and powerful, Hibs have the basis of a side that should become stronger as the season progresses. Fenlon's managerial position is, at least for the moment, assured following the siege that ensued after the battering by Malmo and a poor start to the season.
Celtic will find strength in the manner of the comeback. They may have been annoyed at the manner of the Hibs goal, but were not dismayed by it. Virgil van Dijk, whose ill-considered pass to Scott Brown allowed Thomson to poke the ball through to Heffernan for the opener, was part of a defence that was largely untroubled, with Darnell Fisher, the 19-year-old Englishman, coming in at full-back for the virus-stricken Emilio Izaguirre and proving to be a sharp passer and pacy runner.
Fisher, though, was an indication that Celtic's strength in depth is being tested. The injury sustained by Kris Commons, a hamstring pull that owed nothing to any challenge, robust or otherwise, has sharpened the awkward truth that Lennon's squad is being stretched.
With Brown suspended for tomorrow night's match for his stupid kick at Neymar, Lennon would not have been heartened by the performance of his captain's likely replacement. Biram Kayal ran and passed to little effect and Lennon will be delighted if Mikael Lustig and Izaguirre prove fit enough to return to their positions as full-backs, allowing Charlie Mulgrew to play in midfield.
With Lennon seemingly averse to employing two "lefties" in Mulgrew and the fit-again Joe Ledley in central midfield, Kayal is almost certain to play tomorrow. He needs a strong performance to dispel growing doubts about his efficiency in a Celtic first team. In contrast, the only question mark over Forrest is his susceptibility to illness and injury. The engaging, shy 22-year-old possesses a spectacular talent. Simply but indisputably, he is a game changer.
His equaliser at the weekend was founded on a direct run and embellished by a finish off the side of his right boot. He could have won the game for Celtic with a volley at the back post but Williams saved well.
However, in the absence of Commons, he can bring craft to the Celtic attack tomorrow night. It was Forrest's goal that ensured Celtic would play in the group stages of the Champions League and he has that ability to make the dramatic intervention, whether by shot or cross, that confounds opponents.
With Stokes, Samaras and Pukki all seeming on Saturday to be the victims of what Lennon described as "heavy legs" after international duty, there was a spring in the step of the young winger.
Celtic undoubtedly will face Ajax diminished by the loss of Commons and Brown, but they can find strength in the realisation that the defence is improving, Samaras reserves his best for Europe and Forrest is back. Ajax will provide a challenge that will not resemble the physicality of the weekend but Celtic must overcome it to retain hopes of playing in Europe in any form after the group stages.