The CIA Director's decision to resign over revelations of an affair had me scratching my head yesterday. A reader shot me an email in full agreement, pointing out that, when de Gaulle was informed that one of his ministers was an adulterer he is reported to have said: 'Il fait son devoir comme homme.' ('He does his duty as a man.')

That's the French for you. At President Mitterand's funeral, his wife and mistress stood side-by-side at his grave.

Still, one doesn't need to be quite as forgiving (or sexist) as de Gaulle to be puzzled by Petraeus' resignation, particularly since his predecessor Allen Dulles had over a hundred affairs. And as The Atlantic's Conor Friedersdorf points out, at least three of the last ten presidents were unfaithful. Were they all threats to US national security?

Illustrating a more enlightened approach to such matters, I leave you with this Churchill story, recounted by Stephen Fry: