Not long before his death, Harry and I headed out for a walk that proved eventful. He was nearly 13, old for a big dog. Walks were no longer the slap-happy Iditarodsof his youth, frenzies of purposeless pulling in which we would cast madly off in all directions, fighting for command. Nor were they the exuberant archaeological expeditions of his middle years, when every other tree or hydrant or blade of grass held tantalizing secrets about his neighbors. In his old age, Harry had transformed his walk into a simple process of elimination -- a dutiful, utilitarian, head-down trudge. When finished, he would shuffle home to his ratty old bed, which graced our living room because Harry could no longer ascend the stairs. On these

walks, Harry seemed oblivious to his surroundings, absorbed in the arduous responsibility of placing foot before foot before foot before foot. But this time, on the edge of a small urban park, he stopped to watch something. A man was throwing a Frisbee to his dog. The dog, about Harry's size, was tracking the flight expertly, as Harry had once done, anticipating hooks and slices by watching the pitch and roll and yaw of the disc, as Harry had done, then catching it with a joyful, punctuating leap, as Harry had once done, too.

Harry sat. For 10 minutes, he watched the fling and catch, fling and catch, his face contented, his eyes alight, his tail a-twitch. Our walk home was almost {lcub}hellip{rcub} jaunty.

Some years ago, the Style section invited readers to come up with a midlife list of goals for an underachiever. The first-runner-up prize went to:

"Win the admiration of my dog."

It's no big deal to love a dog; they make it so easy for you. They find you brilliant, even if you are a witling. You fascinate them, even if you are as dull as a butter knife. They are fond of you, even if you are a genocidal maniac. Hitler loved his dogs, and they loved him.

Puppies are incomparably cute and incomparably entertaining, and, best of all, they smell exactly like puppies. At middle age, a dog has settled into the knuckleheaded matrix of behavior we find so appealing -- his unquestioning loyalty, his irrepressible willingness to please, his infectious happiness. His unequivocal love. But it is not until a dog gets old that his most important virtues ripen and coalesce. Old dogs can be cloudy-eyed and grouchy, gray of muzzle, graceless of gait, odd of habit, hard of hearing, pimply, wheezy, lazy and lumpy. But to anyone who has ever known an old dog, these flaws are of little consequence. Old dogs are vulnerable. They show exorbitant gratitude and limitless trust. They are without artifice. They are funny in new and unexpected ways. But, above all, they seem at peace.

Kafka wrote that the meaning of life is that it ends. He meant that our lives are shaped and shaded by the existential terror of knowing that all is finite. This anxiety informs poetry, literature, the monuments we build, the wars we wage, the ways we love and hate and procreate -- all of it. Kafka was talking, of course, about people. Among animals, only humans are said to be self-aware enough to comprehend the passage of time and the grim truth of mortality. How then, to explain old Harry at the edge of that park, gray and lame, just days from the end, experiencing what can only be called wistfulness and nostalgia? I have lived with eight dogs, watched six of them grow old and infirm with grace and dignity, and die with what seemed to be acceptance. I have seen old dogs grieve at the loss of their friends. I have come to believe that as they age, dogs comprehend the passage of time, and, if not the inevitability of death, certainly the relentlessness of the onset of their frailties. They understand that what's gone is gone.

What dogs do not have is an abstract sense of fear, or a feeling of injustice or entitlement. They do not see themselves, as we do, as tragic heroes, battling ceaselessly against the merciless onslaught of time. Unlike us, old dogs lack the audacity to mythologize their lives. You've got to love them for that.

At the pet store, we chose Harry over two other puppies because, when wrestling with my children in the get-acquainted enclosure, Harry drew the most blood. We wanted a feisty pup, and we got one.

It is instructive to watch what happens in a tug of war between a child and a young dog who is equally pigheaded, but stronger. Neither gives an inch, which means that, over dozens of days, the child is dragged hundreds of feet on his behind.

The product of a Kansas puppy mill, son of a bitch named Taffy Sioux, Harry had been sold to us as a yellow Labrador retriever. I suppose it was technically true, but only in the sense that Tic Tacs are technically "food." Harry's lineage was suspect. He wasn't the square-headed, shiny, elegant type of Labrador you can envision in the wilds of Canada hunting for ducks. He was the shape of a baked potato, with the color and luster of an interoffice envelope. You could envision him in the wilds of suburban Toledo, hunting for nuggets of dried food in a carpet.