In Walt Disney’s Fantasia, the apprentice Mickey Mouse bashfully hands back the sorcerer’s hat after failing to stop a troupe of magic broomsticks from causing a flood. Mark Zuckerberg made his own bow to the US Congress on Tuesday by apologising for the havoc that he has unleashed at Facebook.

Mr Zuckerberg once gave the impression of being supremely in charge of his company, down to his control of its voting shares. Even when something went wrong and he had to backtrack, it felt like a mere adjustment to his master plan. Lately, he has looked more apprentice than sorcerer.

“Social networks can have properties that are neither controlled nor even perceived by the people within them,” Nicholas Christakis and James Fowler observe in their book Connected. Or by those in charge. The troubling thing is not that Mr Zuckerberg at first downplayed Russian efforts to affect the US presidential election, but that he did not understand them.