I didn’t think about it at all. I have a hard time recognizing that I’m 84, almost 85. I’m in complete denial, which I think is extremely useful. Of course from time to time I allow myself to be aware of it, but it’s not something that I dwell on. I like working. I work very intensely.

I think I’ve learned more about how to make a movie. The basic approach hasn’t changed. The method that I follow is the same one that I’ve always followed. I hope that I’ve learned from one movie to the next, at least enough not to make the same mistakes.

The portraits here are of men and women in their 80s and 90s, rich in the rewards of substantial and celebrated careers, and although I know none of them except by name and reputation, I’m asked why their love’s labor is not lost but still to be found. Why do they persist, the old masters? To what end the unceasing effort to discover or create something new? Why not rest on the laurels and the oars?

The short answer is Dr. Samuel Johnson’s, in a letter to James Boswell in 1777: “Depend upon it, sir, when a man knows he is to be hanged in a fortnight, it concentrates his mind wonderfully.” A longer answer is that of the 19th-century Japanese artist Hokusai, who at 75 added a postscript to the first printing of his “One Hundred Views of Mount Fuji”:

“From the time that I was 6 years old I had the mania of drawing the form of objects. As I came to be 50 I had published an infinity of designs; but all that I have produced before the age of 70 is not worth being counted. It is at the age of 73 that I have somewhat begun to understand the structure of true nature, of animals and grasses, and trees and birds, and fishes and insects; consequently at 80 years of age I shall have made still more progress; at 90 I hope to have penetrated into the mystery of things; at 100 years of age I should have reached decidedly a marvelous degree, and when I shall be 110, all that I do, every point and every line, shall be instinct with life — and I ask all those who shall live as long as I do to see if I have not kept my word.”

Hokusai died in 1849 in his late 80s, by all reports still far from satisfied with his work then in progress. I’m not surprised. When I was 6, I delighted in the act of writing, at 12, in the expecting that by the time I turned 21, I would know how to make of it an art. The birthday came and went, and no dog showed up with the bird in its mouth. Before I was 30, I’d written seven drafts of a first novel mercifully unpublished; I consoled myself with the thought that by the time I was 40, I would know what I was doing. Another dream that didn’t come true, and so when I was 45, I began to explore the uses of the essay, the term from the French essayer (to try, to embark upon, to attempt), the form experimental and provisional, amenable to multiple shifts of perspective and tone, and therefore the best of instruments on which to practice the playing with words. The essay proceeds from the question “What do I know?” and doesn’t stay for an answer until the author finds out what he means to say by setting it up in a sentence, maybe catching it in the net of a metaphor.

On the way through my 50s I could see signs of progress, producing manuscripts that required only extensive rewriting, not the abandonment of the whole sorry mess of a dumb idea. Revisions pursued through six or seven drafts allowed for the chance to find the right word, to control the balance of a subordinate clause, to replace the adjective with a noun. I didn’t enlist the help of a computer because words so quickly dressed up in the costume of print can pretend to a meaning and weight they neither enjoy nor deserve. Writing with a pen on paper, I can feel the shape and sound of the words, and I’m better able to judge how and why one goes with another, and on approaching the age of 70 I toyed with the hope that success was maybe somewhere not far away in a manger or on the near side of a rainbow.

Now I am 79. I’ve written many hundreds of essays, 10 times that number of misbegotten drafts both early and late, and I begin to understand that failure is its own reward. It is in the effort to close the distance between the work imagined and the work achieved wherein it is to be found that the ceaseless labor is the freedom of play, that what’s at stake isn’t a reflection in the mirror of fame but the escape from the prison of the self.

T. H. White, the British naturalist turned novelist to write “The Once and Future King,” calls upon the druid Merlyn to teach the lesson to the young prince Arthur:

“You may grow old and trembling in your anatomies, you may lie awake at night listening to the disorder of your veins, you may miss your only love, you may see the world about you devastated by evil lunatics, or know your honour trampled in the sewers of baser minds. There is only one thing for it then — to learn. Learn why the world wags and what wags it. That is the only thing which the mind can never exhaust, never alienate, never be tortured by, never fear or distrust, and never dream of regretting.”

The lesson can also be drawn from the strength of the work done in the dying of the light by the octogenarian and nonagenarian students of the several and various arts — by, among others in a very long list, Michelangelo, Titian, Thomas Hardy, Claude Monet, Georgia O’Keeffe, Donatello, Pablo Casals, Jasper Johns, Giuseppe Verdi, Toni Morrison and Picasso.

John D. Rockefeller in his 80s was known to his business associates as a crazy old man possessed by the stubborn and ferocious will to know why the world wags and what wags it, less interested in money than in the solving of a problem in geography or corporate combination. By sources reliably informed I’m told that Warren Buffett, 84, and Rupert Murdoch, 83, never quit asking questions. Sophocles in his early 90s wrote “Oedipus at Colonus”; the American journalist I. F. Stone began the study of ancient Greek in his 70s in order that he might read the play in the language of its birth. Stone, the most relentless investigative reporter of his generation, had uncovered the truth known to both Hokusai and T. H. White, and the lesson I’m now almost old enough to learn: that the tree of knowledge and the fountain of youth are one and the same.