Or, to take a cultural example, when Shirley Temple made the films that landed Graham Greene in so costly a legal wrangle that it bankrupted the magazine Night and Day (he had made a libellous insinuation about her sexual appeal to middle-aged male spectators), she was unquestionably precocious for her age, both her own and the age - the period - in which she lived. Nowadays, she would probably be regarded as something of a late developer (and that goes for the matter of her sexuality).
Even curiouser, the same process has transformed literature. Fiction written for adults has inexorably rejuvenated itself (the rhetorical orotundity of a Henry James would be inconceivable in a contemporary novel).
Children's fiction, on the other hand, even that intended for the tiniest of tots, now treats as a given, as an irreversible fait accompli of our radically altered world, social attitudes and linguistic manners which, a half-century ago, if they had been sanctioned at all, would have remained the exclusive preserve of adolescents.
Which is the first reason why Enid Blyton is destined for posterity's chop. It would doubtless surprise us to learn just how many children continue to enjoy the adventures of Noddy and Big Ears, the Famous Five, the Secret Seven, Malory Towers, etc. Even so, she wrote for a species of child that barely exists any longer and will have become utterly extinct well before the end of the next century.
And the second reason? The poet Brian Patten, a fan, was nevertheless forced to concur that Blyton's characters were "wooden", her villains "stereotyped", her prose "repetitive and clumsy and bigoted". The problem isn't at all one of political correctness (the impact of which will almost certainly be neutralised as the years, the decades and the centuries elapse). No - as witness the pantheon of Carroll, Barrie, Kenneth Grahame and company - children's fiction survives for precisely the same reason as adult fiction: because it is well written. QED.