On the face of it, it was straightforward enough. Was there one race where in his illustrious running career, chockful of world records and medals, he felt his finest race, the best he possibly could? One race which stood out as thepinnacle of achievement.
Eventually the answer came.
"Rome. That fits it," he said from his home in Dallas.
"I gave it everything that day and couldn't have done any better."
That is appropriate, given that next Thursday, September 2, is the 50th anniversary of the day New Zealand's Athlete of the Century ran his finest race to win the 800m gold medal at the 1960 Olympic Games.
It was an Olympic record too, 1min 46.3s.
The world was at the powerful 21-year-old's feet.
Within an hour, a splash of New Zealand glory had been doubled, with Sir Murray Halberg triumphing in the 5000m, in 13min 43.4s.
It was, and remains, New Zealand athletics' golden hour, probably never to be repeated.
Halberg had won the 1958 Empire Games 5000m gold in Cardiff, and backed that up at Perth in 1962. He had been a favoured runner in Rome. He had the reputation.
Snell was different. He was unknown.
Had he wanted to thrust his name on the world athletic stage, he could not have done it any more dramatically.
Two gold medals followed at the Tokyo Olympics four years later, world records were snared in Wanganui, Christchurch and Auckland.
Within a year he was gone, at 26, but even though he's lived in the United States for 36 years, he's far from forgotten.
Both men were guided by the forthright Arthur Lydiard, who revolutionised running.
Besides Rome, Snell vividly recalls the race which shaped his life.
"I'd just turned 19 when I won the 880 yards competing for Waikato against Auckland," he said.
"My old mate Michael Macky came rushing down from the stands and said 'we've got to get you alongside Lydiard'."
From that came a remarkable partnership.
"I would not have had my career if not for him," Snell said of Lydiard this week.
