Almost two years ago, I was lucky enough to tour Mount Vernon with a dozen people including him. (If I were David McCullough I would know the date and time. But I know the weather.) At the bottom of a stairway leading to the second floor, we chatted for a moment, and I asked him how he accounted in his imagination for the amazing fact of the genius cluster that founded our nation. How did so many gifted men, true geniuses, walk into history at the same time, in the same place, and come together to pursue so brilliantly a common endeavor? “I think it was providential,” he said, simply.

Well, so do I. If you do too, it’s part of what you’re celebrating today.

Later, after dusk, an unforgettable moment. The Mount Vernon Ladies Association, led by Gay Gaines, retiring after three years as one of its greatest regents—she’d worked herself like a rented mule to solidify and expand the operation—gave us dinner on a long table on the piazza, the veranda overlooking the unchanged Potomac. It is where President and Mrs. Washington dined. It was hot, and now dark, and David McCullough rose to speak of Washington, of his courage and leadership. A storm had been gathering all day. Now it broke, and as he spoke of Valley Forge there was, literally, a sudden roar of thunder, and lightning lit the clouds over the river. Mr. McCullough continued, with his beautiful voice, and we all got a chill: What kind of moment is this? What could we possibly have done to deserve it?

Nothing of course. Some gifts are just given.