The first time I ever visited the great hall of New York City’s Cooper Union, I was not yet a teenager, but I was already mad to learn everything I could about the most famous man who ever appeared there. Abraham Lincoln’s 1860 Cooper Union address—his first and only campaign speech in New York—dramatically introduced the Western leader to the East. For Lincoln, it proved a personal and political triumph.

I knew few details about this milestone speech when I made my own maiden pilgrimage. But even in the early 1960s—it was, after all, the era of the Civil War Centennial—I already knew that it had somehow helped make Lincoln President. Today, having just spent three years researching and writing a new book on this very subject (Lincoln at Cooper Union: The Speech That Made Abraham Lincoln President), and after countless return visits, I can confirm that my infant impressions were pretty much on the mark.

Cooper Union was Lincoln’s watershed, the event that transformed him from a regional leader into a national phenomenon. Here the politician known as frontier debater and chronic jokester introduced a new oratorical style: informed by history, suffused with moral certainty, and marked by lawyerly precision.

My guide for my long-ago visit was my older first cousin, Gerald Ehrenstein, now a retired physicist, then a recent Cooper Union graduate eager to show me his alma mater. After a long subway ride downtown and a march through the quaint lobby and down a flight of stairs, here at last was the shrine: a cavernous yet somehow claustrophobic basement auditorium from whose stage Lincoln had aroused his audience with the cry “Right makes might.”

I never forgot the visit. But I didn’t see the Great Hall again until 1977, when I was the young, absurdly self-assured press secretary for Bella Abzug, then running for mayor of New York in a crowded field of men. That autumn a civic group hosted a mayoral debate there. Newspapers breathlessly reported that the eventual winner might well, like Lincoln, emerge from the Cooper Union test marked by destiny.

Before us that night sat eight candidates for City Hall: Bella, Rep. Ed Koch (who went on to win the election), state senator Roy Goodman, the future governor Mario Cuomo (for whom I would one day work as well), the harried incumbent, Abe Beame, the local leaders Percy Sutton and Herman Badillo, and a businessman named Joel Harnett.

The debate was in full swing when a young man suddenly came racing down the aisle, carrying an object in his right hand. In a flash, he reared back and hurled it toward the debaters. It turned out to be a harmless apple pie, which did nothing worse than splatter Beame and Abzug. Miraculously, almost simultaneously, Cuomo leaped off the stage and flew at the prankster, whom he knocked to the ground before startled police officers joined the tangle to hustle him away.