And at some point that afternoon, in front of a case with a model of a Saturn V in it, he explained staging to me for about six minutes without stopping.

My father built model aircraft.

Not rockets — balsa aircraft, from plans, for about forty years, in a garage in Wilmington with a radio on.

And there is a specific thing that a person does when they are explaining a mechanism they love to somebody who does not know about it, which is that they stop looking at you and start looking at the middle distance and their hands start describing shapes.

My son did that in front of a display case in Raleigh at the age of seven, and it was my father’s hands, and my father had been dead for eight years and had never known this boy existed.