Both men seem to have the condition that afflicts so many officeholders who get into trouble, from Clinton to Foley to Sanford to Spitzer: a sense of invincibility, and a belief that the usual rules don’t apply to them. They take ever bigger risks, as if it is a form of thrill-seeking, or they can no longer gauge risk.

Weiner’s was particularly flamboyant: On the day in 2010 when the House voted to approve Obamacare, and Republican lawmakers stood on the House balcony riling a tea party crowd below, Weiner showed up and taunted the gathering. “I feel like Mussolini now!” he said.

The narcissistic strain is common, and it predates the rise to power. It takes a certain personality to believe that one is meant to lead. This is reinforced once in power by sycophantic staffers. The problem has become worse as congressional redistricting leaves more lawmakers with safe seats, but the phenomenon is not Washington’s alone: McDonnell honed his invincibility in Richmond, and Weiner continued his behavior after resigning his House seat.