We knew the cost of Sergio Aguero to Manchester City but we couldn't know his value to the richest football club in the world. Now we can. Now it hits us in the face with the force and the urgency of his brilliant 30-minute intervention in his new club's 4-0 opening Premier League victory over Swansea City, a team of quite affecting fluency right up to the moment Diego Maradona's son-in-law turned them into so many pieces of splintered matchwood.
It is true that no one player, not Pele or Di Stefano or George Best made a team, but it is also right that he can change, utterly, the way it thinks about itself. This is the promise made by Sergio Aguero.
With such a man on the field it will surely be that much easier for City to believe they are indeed ready to compete at the highest level.
The scale of his impact and potential meaning was only partly to do with the evidence of perfect technique and, at least on this occasion, ravenous hunger. There was also the joy, the explosion of camaraderie in a team which previously might have picked a whole series of arguments at the Last Supper. The new man suddenly made anything seem possible.
It is that sensation when a new player arrives and all those who play alongside him, and those who merely watch, feel a gust of not hope but certainty. Zinedine Zidane did that when he arrived at the Bernabeu, as did Marco van Basten at San Siro and Dennis Bergkamp at Highbury.
No, you're right, we shouldn't get carried away. Aguero will doubtless face much heavier challenges than the one provided by the newly promoted Welsh club but this is no reason to hold back a powerful suspicion.
It is that when set against all of City's wealth, and their previous predilection for throwing such great lumps of it at players of questionable talent and extremely troubling personality, the £38m signing of Aguero already looks like stunning good value.
This is because what Aguero did in a few minutes was something that had proved beyond the powers of such as Carlos Tevez, Yaya Touré, Gareth Barry, James Milner and Mario Balotelli, especially Balotelli, and manager Roberto Mancini.
It is not to dispute such varied talents, only to say that Aguero's astonishing gift was to slash away all that talk of two-, three-, four-year plans and a slow march to the peak of English and European football, and say that there is only one way to push back the horizons of even the most expensive football team, and that the time when you do that is not tomorrow but today.
What you do, if you crave the transforming moment, is inject into your team an authentically inspiring player, one who has both the talent and self-belief to impose on any situation. Even in their march to Champions League qualification and their first significant trophy in 35 years, City so often displayed the body language of doubt. Their bench resembled a dressing station for the wounds of the psyche.
Tevez sulked and pouted in between telling thrusts on the field. Balotelli was at best a dubious asset. David Silva, for all his lovely, acute touch, must have felt he too often performed in the company of strangers.
He had no reason to feel such a weight when Aguero helped him on his way to his man-of-the-match award with an assist which came straight from the football heavens. Balotelli never made it on to the field and even he might have understood the reason for his idleness when Aguero scored his two goals with a stunning combination of bite and technical brilliance.
For Mancini, such a performance was both deliverance and a challenge. He was freed from the oppressive sense that City remained a team falling short of optimum performance – an impression only deepened by their halting effort against Manchester United at Wembley – but also obliged to build on the inspiration provided by his new man.
The most enduring criticism of Mancini is that if he understands football, as a former player of perfectionist leanings, he grasps less well the need to liberate a team from its own inhibitions. There was much of that requirement in evidence again before Aguero was sent out to introduce himself.
He put down a calling card of exquisite simplicity. He said what he could do and the manner in which he would do it. When it was over he thanked his new fans and said he was anxious to earn their trust out on the field, the only place where it really mattered.
No, one man doesn't make a team. But he can redefine its values and set new standards and what would any top club pay for that? City – for once in their new life – must feel they have parted with just a little loose change.