The late William Greer was born in 1909 in Stewartstown, a village in Northern Ireland. At 20-years-old, he left behind his homeland with a heavy and hopeful heart to emigrate to the United States.

Greer came to serve and support many well-known Boston and New York families as a chauffeur and family confidant. After service in the Second World War, he joined the US Secret Service in 1945. As a Secret Service agent, Greer performed exceptionally, and eventually came to be a part of President John F Kennedy’s detail in the early 1960s. He was close with President Kennedy and Jacqueline Kennedy.

On the 22nd of November 1963 in Dallas the weather started off damp. Greer was tasked with driving the Kennedys through the streets of Dallas in the presidential limousine. The people of the city were jubilant and heartfelt in welcoming President Kennedy and the First Lady. It seemed as if the shinning presence of the glamorous couple willed away the grey clouds and rain.

Greer proceeded along the carefully planned presidential route in Dallas. He turned right onto Houston Street along the edge of Dealey Plaza, then turned left onto Elm Street at the Texas School Book Depository. The air was full of excitement as the open-top vehicle moved along. It was right at this instant that the agent who sat to Greer's right yelled out that the president had been hit.

While still driving, Greer turned around to see President Kennedy slouched over. Then the fatal shots came. The vibrant 35th President of the United States was dead. Dark clouds of grief descended over America and the world – the shine of hope dipped behind the gloom.

Like the country and world that grieved following that dreadful day 60 years ago in Dallas, William Greer shouldered deep sorrow. As many who were close with the Kennedys or part of the family, the Northern Irishman, who became a proud American, was traumatised by the tragedy right up to the end of his life in 1985.

Here we are now in this moment far removed from those times. Many who lived through those events are gone, and those who clearly remember them have lived a long life and experienced many challenging world events. I stand here at the Kennedy Grave Memorial at Arlington National Cemetery in Arlington, Virginia. I scan the serene scene, watch the flicker of the eternal flame, observe the diversity of people quietly moving around with deep reverence. I read these words from President Kennedy written in stone at the burial site: “The energy, the faith, the devotion which we bring to this endeavour will light our country and all who serve it — and the glow from that fire can truly light the world.”

Our world needs hope. We long for messages that glow with optimism, search for enlightened ideas that remind us of our possibilities, grasp for words that value service. The early sixties were complex times with so many still being denied fundamental freedoms, equality, and justice. Returning to those times whether that be in the US, Scotland, or other locations would be to take a significant step backwards.

However, political leaders today can learn much from President Kennedy, and the flame of hope he cultivated and embodied. His message was not a message of division which characterizes the current political tone that many politicians embrace. He was motivated by what people can achieve when yoked together.

And while we should be realistic and never place too much stock in the words of any political leader, we can demand they refrain from overzealous partisanship, bullying, and hateful rhetoric. And we can hold up those leaders who forge unity and act with compassion.

When Kennedy spoke of a flame, he did not mean for it to be used as a weapon to burn others, but rather for it to keep the vulnerable warm, to comfort society, to spur confidence, and to light a peaceful path forward for all.

Ian Houston is an honorary professor at the University of the West of Scotland and an honorary lecturer at Aberdeen University.