The photograph was of failure. The photograph was on the wall in his room. The photograph was of him falling during the 1,500m at the 1996 Atlanta Olympics where he finished last. As Hicham El Guerrouj, the double Olympic gold medallist from 2004 whose 1,500m world record has stood for 19 years, told me once: "(The photo) was part of my story... It was also there to motivate me."
Athletes use anything they can to spur themselves - a photograph, their poverty, a handshake from a childhood hero or just an imagined slight. They don't just swim or run for the heck of it, but often for a cause. To fulfil their potential, to buy a house, to make a little history, to own a single medal.
Or to beat one athlete.
Athletes are pushed and prodded and consumed by rivals who live in their heads like wandering ghosts. To the point where Jurgen Hingsen, the great decathlete, told The Daily Mail laughingly that his legendary rival, Daley Thompson, kept a photo of him at home. In his toilet.
Joseph Schooling doesn't have to go quite as far but maybe he should pin a picture of Caeleb Dressel to his wall. A sort of sporting WANTED poster. The man he has to catch. Better still, perhaps he should affix Dressel's 100m butterfly time of 49.86 seconds to the bottom of his bed as a daily reminder of his next destination.
Schooling for six months has been a man in search of a cause. For years his labour had a single purpose, Olympic gold, and incredibly it had come.
Now Dressel. Now a new rival to pursue. Now an opponent whose victory in the 100m butterfly is actually a gift to Schooling. It gives the Singaporean a cause, it could drive him harder through the cold water, it might help him find an edge, it may offer him an extra incentive, it could make him do that extra sit-up even when his body is crying.
The better athlete drives you because he's standing on the part of the podium you thought was reserved for you. The better athlete annoys you, impresses you, intimidates you and inspires you by making you feel insecure. Did I practise enough? Should I do one more mile?
In 2009 in The Telegraph, Sebastian Coe, the two-time Olympic champion, wrote about running 19km on a Christmas morning during the harsh winter of 1979. He returned, he showered, he relaxed. Then, unsure, he thought, maybe Steve Ovett, his most formidable rival, was doing two training sessions that day. So Coe put on his shoes again , "faced the snow and ice" and trained for a second time.
Years later, as he wrote, he told Ovett the story over a meal and his rival laughed and said: "Did you only go out twice that day?"
The rival can become an object of envy, of fascination, even of dislike. And yet to chase him is in fact to honour him, to use him as a standard is to show humility. Larry Bird, the Boston basketballer, told Sports Illustrated that "the first thing I would do every morning during the season was look at the box scores to see what Magic (Johnson) did". In Los Angeles, Johnson was reading the papers, too, and said: "If (Larry) had a triple double, I knew what I'd want that night." Men were lifting their sport by raising each other.
Schooling wanted to chase a retired god in a record book (Michael Phelps' 100m butterfly time) but this is an even better challenge, a human called Dressel in the next lane who looks like a hunk of recently dynamited, chipped rock on which someone has spray-painted an eagle. The American is a majestic mix of stamina, strength, versatility, purpose and it should be enough to rouse Schooling's competitive spirit. Athletes learn from each other after all, and just this year that old sage Roger Federer confessed that Rafael Nadal had made him a better player.
Schooling took a mental break after Rio, doused his afterburners and the world went past him. But he has worn defeat with grace and honesty and has not hidden behind the cheap armour of excuses. A young champion is still finding his way to his consistently best self.
The swimming pools of the world are scary places, inhabited by fellows like breaststroker Adam Peaty whose push-up tells you the power at work in the water. If you haven't seen the Instagram video, Peaty lowers himself in conventional style but then pushes upwards so powerfully that his entire body flies a few feet into the air and hangs parallel to the ground. What is he made of? Steel springs?
It is these sort of people, with a manic work ethic and desperate drive, that Schooling will keep confronting. He will not fear them because he has beaten them before and yet talent has to be continually polished and displayed. His ego is hurt, his pride dented, and if he puts a photograph of Dressel's timing up in his room, he should also look in the mirror. What he will see is a picture of an Olympic champion. What he must remember is how he became one.