I passed him once, in Boston’s Public Garden. His was the attire of a retired professor - tie and tweed jacket. He looked as though he had been called back to the classroom to deliver one final lecture.

In many ways David McCullough’s latest book, History Matters, feels exactly like that. A posthumous collection of selected speeches and essays, History Matters is a moving coda to McCullough’s body of work. In reading it recently, I completed the McCullough catalogue - all 13 books and over 6,000 pages of it.

I’m not writing this to tell you that I read all these pages so that you don’t have to. No. Doing so would suggest that there exists a sole interpretation of McCullough’s work and that I possess the key to the code.

I don’t.

Rather, I’m writing this as an inducement for you to at least dip your toe into the gently flowing but unceasing river of ink that McCullough hammered out on his Royal Standard typewriter. You can do so out of general interest in American history, or out of curiosity for what narrative non-fiction sounds like at its best, or to peruse the work of a two-time winner of the Pulitzer Prize as well as the National Book Award, or any number of other reasons.

As for me, a big part of my interest in turning to McCullough is nostalgia.

I was first drawn to McCullough for the presence of his Truman biography on my grandfather’s bookshelf. It was just about the biggest book I had ever seen, all 996 pages of it. While it would be years before I read it, I would pass by it as a kid with some understanding that I would one day accept the challenge that it posed by being on the shelf. It was as though it was saying, Read me. I dare you.

I never asked my grandfather why he had the book, but perhaps it’s not surprising for a Marine who fought in the Pacific in World War II to read a book about the man who ordered the use of the atomic bomb - twice - against the Japanese. Perhaps it’s not surprising for a man who otherwise would have been part of the invading force of the Japanese home islands to learn more about the man whose decision averted such an invasion and spirited him home to the woman he would marry.

In the final years of her life, my grandmother kept a copy of David McCullough’s John Adams in her room. I think there was something about the fact that she used to live in Quincy, where the Adams Family lived and where their homestand still stands, that made her feel a kinship with both John and Abigail Adams.

She was determined to read the book through, but never did.

She did, however, get through the opening - and what an opening! Even the first part of the first sentence still makes me shudder for the chill of the winter night McCullough describes on the coast road to Boston (“In the cold, nearly colorless light of a New England winter…”). Just seeing the spine of the book on my bookshelf brings me back to the soft light filtering into my grandmother’s room, her green couch, her hearty New England-ness, her unfailing good cheer.

While my grandparents and Mr. McCullough have since passed from the stage, their legacy lives on. McCullough’s books serve as a link to a history that my grandparents helped shape, that their grandparents before them lived through, and that their grandparents’ grandparents experienced. If, as McCullough says in History Matters, “History is human,” reading McCullough also makes history personal.

Again and again throughout his books, McCullough reminds the reader that nothing had to happen the way it did, that history is not some inevitable march towards some inevitable outcome. How could it be if a man like Harry S. Truman became President of the United States? Again and again, McCullough reminds us that it’s people - strong, courageous, resilient people - who made the history we’ve come to know. People like Theodore Roosevelt, people like Orville and Wilbur Wright, people like Harriet Beecher Stowe, and George Washington, and Abigail Adams, and Willa Cather, and Manasseh Cutler, and Washington Roebling.

And yes, in their own way, people like my grandfather and grandmother as well.

These are men and women who accepted hardship, turned challenges into opportunities, and gave rise to the hopes of a nation. They acted in such a way that echoes a sentiment George Washington liked to quote from Joseph Addison’s Cato, “’Tis not in mortals to command success, but we’ll do more, Sempronius, we’ll deserve it.”

It’s in the striving of the deserving that history - real history - is made. Truman, McCullough, and my grandparents had no patience for superficiality, no patience for individuals so undeserving of success, no patience for a man like Joseph McCarthy, who Truman referred to as “a ballyhoo artist who has to cover up his shortcomings by wild charges.” For them - for us - the lever of history is set on a fulcrum of character.

Deserving their legacy, deserving success, is a challenge we can set ourselves to in our time, in our lives. We can set ourselves to the challenge with the same determination of two brothers who ran a bicycle shop and taught the world how to fly. We can set ourselves to the test with the same fortitude of a couple who raised seven kids in a triple-decker in Dorchester. We can set ourselves to the task before us with the same persistence of a man who labored for years over his books to help us better understand the past so that we may better navigate the present and the future.