As for the rest of her e-mail correspondence, we may never know what’s in there. Much of it, I’m sure, is legitimately private and none of our business. Some may fit into a public-private gray area. Some may be about the foundation. All of it, however, is firmly in Clinton’s possession — the e-mail server reportedly sits in one of her homes — and therefore she has the advantage in any fight over disclosure.

When Clinton became secretary of state in 2009, she was still recovering from a bruising and unexpected defeat in the Democratic primaries the year before. The prospect of another presidential run must have seemed distant and uninviting, perhaps like spending two years pounding oneself on the head with a hammer. Yet something — some impulse — compelled her to lock down her e-mail communications so they would always remain in her control.

Long after Republicans punch themselves out over Benghazi, after questions about Clinton Foundation funding are either answered or deemed unanswerable, after Clinton either cruises to the nomination or fools everyone by not running, the mystery will remain: Why does she act as if she has something to hide, even when she doesn’t?