Arsenal could not defeat Barcelona, but they indicated to others that the feat can be accomplished. It is a lesson that ought to have been absorbed already, since Internazionale knocked out the then Champions League holders in the semi-finals last year before going on to take the trophy for themselves. That, however, was a tie in which José Mourinho's side had all their thoughts on defence for the second leg, with the 1-0 loss sufficient for an aggregate win.
That approach is not consistent with Arsène Wenger's usual attitude, but his own methods almost succeeded on Tuesday even though the draconian dismissal of Robin van Persie had cut them to 10 men. At the very end, a better striker than Nicklas Bendtner would have scored from Jack Wilshere's pass instead of being so clumsy that the challenge from Javier Mascherano became feasible.
It must be stressed that Barcelona were a far superior side who deserve their place in the quarter-finals for following a 2-1 loss at the Emirates with the 3-1 victory at the Camp Nou. Indeed they were a great deal more wasteful on their own pitch than Arsenal's. There was almost nothing for Wenger's attackers to squander and the visitors did not contrive a shot on target, with their goal put into his own net by Sergio Busquets.
While Barcelona's style is to be savoured for its intelligence and technique, the tie with Arsenal confirmed, in a different way from the clash with Internazionale, that they are not unassailable. On occasion, they can be one-dimensional, even if it is the most chic of dimensions. The consciousness of that flaw was reflected in a supposedly incongruous acquisition.
In 2009, Barcelona paid £40m for Zlatan Ibrahimovic and also included Samuel Eto'o in the deal with Internazionale. The forward has about him the air of the traditional predator and the Spanish club will have felt they lacked that trait, even if Lionel Messi is proving that prolific scoring sits easily with technical virtuosity.
Last summer, a move on loan to Milan brought Ibrahimovic to his sixth club in 10 years. Any relationship with Pep Guardiola had foundered. All the same, the initial enthusiasm for the Swede showed an understanding within the Camp Nou that Barcelona must guard against the risk, on a bad day, of becoming a self-parody.
Glorious as the side's well-articulated moves can be, it is absurd to speak as if Guardiola's line-up were the culmination of the sport's evolution. The berth in the last eight of the Champions League is well merited, but they still came near to elimination despite the fact that Arsenal were down to 10 men. The referee, Massimo Busacca, evidently decided that Van Persie, in the bedlam of a ground with 95,486 spectators, had heard the whistle for offside and wilfully went on to try a shot. A second caution was administered.
Even that did not make Barcelona wholly unassailable. They are in the last eight by rights, but a more ruthless side than Arsenal would have had the audacity to score a late decider. It has to be borne in mind that the hosts were employing a makeshift central defence, even if the left-back Eric Abidal is an excellent deputy when he has to go into the middle.
The hindrances were more severe for Arsenal. Theo Walcott was one of those unfit to play, although Wenger would have craved his speed on the counterattack. In addition, it was obvious that Van Persie and Cesc Fábregas were not in peak condition even if they did happen to be on the field at kick-off. Much went wrong for the Premier League side, including the dislocated finger that forced the replacement of the goalkeeper Wojciech Szczesny with Manuel Almunia.
Barcelona could not stifle Arsenal's hopes completely. The match was a reminder that neither Guardiola's side nor any other club is to be taken as the apotheosis of football. The sport has compelled for so long because of its very diversity. Barcelona might not plan to score with, say, thundering headers from old-fashioned centre-forwards after well-aimed crosses by wingers, yet that too is an authentic if now rare delight. For the sake of public interest and the variety of the sport, it is essential that games with Barcelona should not all be played on Guardiola's terms.