Just three days after John F. Kennedy's assassination, while the United States was still paralyzed by shock, Jackie Kennedy made a decision that many considered too risky.

He wanted the world to see leaders walk.

The security men tried to convince her to give up. The Dallas bombing had just happened, the investigations were still ongoing and no one could exclude the danger of a new attack. Organizing a long procession on foot in the heart of Washington seemed an unthinkable choice.

But Jackie Kennedy had another idea.

She was convinced that, at such a dramatic moment, the country should not transmit fear, but strength and continuity.

Thus, on November 25, 1963, the funeral procession moved from the White House to St. Matthew Cathedral with the greats of the Earth who walked behind the fereter wrapped by the American flag.

Among them were the French President Charles de Gaulle, the Emperor of Ethiopia Haile Selassie, Prince Philip and over two hundred representatives from all over the world.

Those images toured the planet and turned that funeral into one of the most solemn and remembered of the twentieth century.

But what strikes today is that almost nothing was left to chance.

In the days following the Dallas tragedy, Jackie Kennedy carefully studied Abraham Lincoln's funeral. He consulted photographs, testimonies and documents of 1865, trying to build a ceremony that was up to a president whose life had been interrupted too soon.

From that research many of the symbols that the world would have remembered were born: the East Room covered in black, the catafalco inspired by the traditions of Lincoln's funeral and the horse without knight, with boots placed on the contrary in the brackets, an ancient military emblem representing a commander who will not return to the saddle.

She was just thirty-four.

Yet he understood a truth that goes beyond that historical moment: the way a nation salutes its leaders contributes to building collective memory.

For millions of people that funeral did not only tell the end of a presidency. He raised the ability of a country to face pain without sacrificing his dignity.

That is why, more than sixty years away, those images continue to be among the most recognizable in American history.