There are many ways of measuring the progress of Cristiano Ronaldo from supreme young narcissist in a game designed for teams into one half of arguably the most dazzling duel that football has ever seen.
One of the more profitable ways, however, is contained within the Munich stadium where tonight he will again seek a place in the same breath that speaks the name of Lionel Messi.
The requirement is to go back six years to when Ronaldo arrived with Portugal for the World Cup semi-final against France. He was booed relentlessly by the England fans who came down from the Ruhr Valley with wounds smarting from England's quarter-final exit, when Ronaldo gave that infamous knowing wink to his bench after Wayne Rooney had been given a red card for stamping on the crotch of Ricardo Carvalho.
Ronaldo was an obvious target for the English, of course, but some of the racket he caused had nothing do with the raw edge of partisanship. It was about the dichotomy that so plainly existed between the talent and the character of the young player who at times seemed to have everything a great footballer could ever want: arresting speed, power, high skill and a beauty of movement and assurance that made all around him seem vulnerable to his force.
Yet so often he betrayed himself. He strutted, he posed and, unforgivably as Portugal fought to regain a foothold, he dived shamelessly when it seemed to be comfortably within his power to equalise. Tonight, as Real Madrid face their most demanding challenge this side of a likely Champions League final with their nemesis, Messi's Barcelona, it is reasonable to believe there will be scarcely a shadow of such a Ronaldo.
Much of that one lingered at Old Trafford before he moved to Madrid in 2009, the pouting, the refusal to mark back, the apparently unbreakable assumption that he operated in his own private world. Yet, of course, Manchester United would learn soon enough the extent of the loss for which a profit of £68m would not begin to compensate.
If there was an iota of doubt about this, it has vaporised in his mano-a-mano contest with the sublime Messi, pictured. That it might just reach a climax in the Champions League final back in Munich in May, that the luminous, endlessly creative Argentine and the relentless Portuguese should share this season the same La Liga total of 41 goals and that Ronaldo has accumulated an astounding 139 goals in 137 games, is something touching the realm of fantasy.
Some will argue that quite a bit of Messi's terrain will always be beyond Ronaldo. It is an argument scarcely weakened by Messi's extraordinary first goal in Barça's weekend defeat of Levante, an instant shot of bewildering power and timing when every door seemed to have been closed. Yet if such burning finesse is beyond Ronaldo, a capacity to score extraordinary goals has long been central to his playing persona.
So why isn't he embraced at the Bernabeu with the kind of passion that used to engulf the beloved Raul and Alfredo di Stefano? Much of the restraint, no doubt, is embedded in the Spanish nature, which prizes above everything the dignity of a great performer.
The Spanish hero, whether he wears a football uniform or a matador's suit of lights, is not supposed to make advertisements for himself. He is not supposed to perform flashy tricks, to exclude both his team-mates and his audience.
Something of this point was made by Ernest Hemingway in his recounting of the "dangeorus summer" of 1959 when the brother-in-law toreros, Luis Miguel Dominguin and Antonio Ordonez, fought across Spain to establish their claims to be No 1. Ordonez was Messi, performing the purest artistry; the older Dominguin was Ronaldo, creating special effects and in the process performing a kind of deceit.
This, however, did not prevent the veteran receiving a wound that was close to fatal, no more than it does Ronaldo producing one piece of evidence after another that beyond all the vanity is a talent as hard as rock.
At Old Trafford there was a much higher toleration level for the excesses of the boy. If he was arrogant and at times feckless, he was also a supreme operator and we have to believe that he is again confident, three years down the road, that he can similarly convince the Real crowd. Certainly, he has shown no inclination to follow in the steps of Jose Mourinho, if and when the coach walks away.
He has been candid in his disagreement with some of the Special One's tactics, especially his belief that Barça's psychological hold over their most serious rivals in Spain and Europe owes a lot to Mourinho's refusal truly to attack them. No, he will not trail after Mourinho, saying, "I don't follow anyone."
Six years ago in Munich such a declaration would have been an example of overweening arrogance. It would have been one more explanation for the abuse that came down from the terraces. Tonight it is just another version of a hard and brilliantly won truth.