The vast majority of clubs cannot afford to match those players’ salaries; those that can are not the sort of teams that tend to buy castoffs. So Juventus, getting desperate, turned to Dybala, Kean and the right back Joao Cancelo: selling players it should want to keep because it cannot sell the players it no longer needs.

Juventus is not the only one of Europe’s aristocrats caught in the trap. Real Madrid does not quite know what to do with James Rodriguez and, in particular, Gareth Bale. Barcelona has been unable to find a home, permanent or temporary, for Philippe Coutinho. Paris St.-Germain does not want to keep Neymar, and he does not want to stay, but their unhappy union may have to continue for some time.

It is easy, in this situation, to blame the players, to say they should all be prepared to drop their salary expectations in order to play the game they love, but that has always had the air of the sort of advice it is rather easier to preach than practice. If you are owed a certain amount of money — however little you theoretically need that money — it is a bold step to forego (a portion of) it willingly, simply because your debtor has decided they do not want to pay it.

It is better, perhaps, to look at the clubs: to ask if perhaps they might use this summer as a learning experience, a chance to fine-tune their recruitment policies, moving away from stockpiling as many players as possible and toward a more focused, scientific, youth-oriented approach.

Elite players nearing their 30s should not be on long-term contracts. They should not be signed for large fees or guaranteed market-defying salaries on a presidential whim. Clubs should not be assembling rosters packed with 25 high-profile senior internationals.

There is a chance that all of this will work out in the end: it might require a spider diagram to explain it, but essentially if Neymar leaves P.S.G. — perhaps with Coutinho or Bale or Rodriguez in part-exchange — then Dybala may move to Paris (or be part of a swap deal for Inter Milan’s Mauro Icardi). All of the dominoes may yet line up just right. Even if they do, though, there is a lesson from this summer for Europe’s great houses. If they do not learn it, they may yet find themselves undone by their own gluttony.