The question of the existence of New York City is one each generation of residents confronts in their own time. The spot on the map remains, the streets still heave with bodies, and the business of the municipality grinds on. But between youth and maturity every New Yorker wakes up to the possibility that the city that possessed them, The Real New York, is gone.

This last month has forced the question on me. What was once one of the city’s pre-eminent restaurants, the Four Seasons, served its last Dover sole in early June, after 60 years. Gloria Vanderbilt, most famous descendant of what was once the city’s pre-eminent family, died not long thereafter, aged 95. Both represented a connection to the middle of the 20th century, when New York ruled the world.

The Four Seasons was already on its way out a few years ago, when it moved out of Mies van der Rohe’s masterpiece Seagram Building. I ate there occasionally when I passed through the world of finance after the turn of this century. The people-watching was as good as advertised, but the magic was the room’s design, by Philip Johnson, which was functionally a time machine: its simple, glowing surfaces sent diners back to a time when Modernism felt new, a postwar moment when New York had the final say on everything and seemed like it would do so forever. A different restaurant occupies it now. I have entered only as far as the bar for a swift martini, for fear that in the course of a full meal the old spell would be broken.