He has no idea what’s coming, but we do. We see John F. Kennedy looking so handsome, so happy, and at the center of the world. His pretty wife seated next to him only adds to the glamour and the anguish. The sun is shining. He appears radiant and looking forward to the future. And we all know that the clock is ticking down. There are less than thirty minutes left. It’s one of the saddest photos of the last century and we see it again and again.

When we view this image today, on what would have been John F. Kennedy’s 90th birthday, we are again transfixed and a little unnerved. It is impossible to grasp — JFK at 90. He is frozen in time — young, attractive, and energetic. His hair never grays, his face never ages.

Over 40 years later, we also know the violence on that day will only multiply in logarithmic dimensions. We will be pulled from that awful moment across a frightening terrain that carries us through more assassinations, more mass shootings … a landscape of death that places its point of origin at Dealey Plaza in Dallas on that sunny afternoon.

Besides the image and the violence, we are also left with the never-ending arguments about his death. Shortly after the assassination of John F. Kennedy, an ocean of writing began to form.

There was the official Warren Report followed almost immediately by the conspiracy theorists countering the government’s point of view and spawning an entire industry. The debate over JFK’s death has been waged in books, movies, and television specials.

There was a second congressional investigation in the 1970s adding thousands of more documents, but no verdict. Ironically, the most substantive information to come out of Capital Hill’s second foray into Kennedy’s death concerned details of his sex life.

Eight Presidents later and living in a new century, the debate hasn’t quieted down. So it should come as no surprise that there are now two new books to add to the mountain of words. First, there is “Brothers: The Hidden History of the Kennedy Years” by David Talbot that offers really nothing hidden at all, but, instead a rehash of information slanted to confirm the suspicions of the conspiracy theorists without actual proof.

And there is “Reclaiming History, The Assassination of President John F. Kennedy” by Vincent Bugliosi which weighs in at an astounding 1,612 pages. Mr. Bugliosi, the man who prosecuted Charles Manson, reaches the same conclusion in all those pages that the Warren Commission came to four decades ago — that Lee Harvey Oswald acted alone. To Mr. Bugliosi’s credit, he goes after the charlatans of the conspiracy belt in detail, naming names and explaining their lunacy. Yet, in the end, nothing changes. Mr. Bugliosi won’t sway those who believe in the conspiracies nor will Mr. Talbot impact those who don’t.

For my money, the best book written on the assassination was William Manchester’s “The Death of a President,” published just three years after JFK’s death. Everyone could have stopped writing after that one. Manchester, one of the great historians of the 20th-century, had extraordinary access to every major character in the drama from Jacqueline Kennedy, one of only two interviews she granted about her husband’s death, to the Dallas policeman who stood guard outside the trauma room at Parkland Hospital.

Manchester spoke to everyone when the events were still fresh in their minds. He sat at the window of the School Book Depository and went to the funeral home that supplied the casket. His detail is astounding.

Perhaps even more important, Manchester had no ax to grind. He was cynical enough from his own experiences in the Marine Corps in Okinawa to be suspect of authority. And at the same time, he was a patriot — understanding the event’s impact on our history while deeply sensitive to the incredible nuances that existed between many of the players in this drama. Above all, he was honest. In the end, Manchester drew the same conclusion as the Warren Commission — the conclusion no one wanted, that Oswald acted alone. It seems impossible to ascribe an event of this enormity which changed our lives and the course of history to a world class dope and cheap failure like Oswald. Just entwining Oswald to Kennedy feels blasphemous. Often, the truth is hardest to grasp.

In the end, the ongoing argument is pointless. Years from now, there will be new conspiracy theorists not yet born and there will be those who will accept the official version. And there will also be people who will stare at the photo, shake their heads, and wonder … what if?

Mr. Kozak lives in New York City.