Image source, Getty Images
Image caption,Nando Parrado and Roberto Canessa hiked for 10 days across the Andes to get help after their plane crashed
Matt Gault
BBC Sport NI Senior Journalist
As Joe Marler alluded to while announcing his retirement last week, international rugby can be something of a "dream bubble".
But towards the end of last month, as the Ireland squad gathered in Portugal and began to look towards Friday's mouthwatering rematch with the All Blacks, they were served a powerful dose of reality.
The Irish squad have had several guests in recent years, from Bono to Shane Lowry. Hearing from personalities outside of the Test rugby grind can be illuminating and light-hearted, a welcome break from training and meetings.
But perhaps no visit stirred their souls quite like Nando Parrado's.
Parrado was once a rugby player, but he is more widely known as a central figure in a story at once inspirational and harrowing, one that exemplifies the strength of human spirit in the face of the greatest adversity.
In October 1972, a plane carrying members and family from Uruguayan club Old Christians Club crashed in the Andes on its way to Chile.
It was a horrible tragedy. Twenty-nine of the 45 people onboard - including Parrado's mother and sister - lost their lives. Those who survived were forced to eat those who had been killed in the crash.
After losing several friends and family members, Parrado and Roberto Canessa, in a desperate bid to find help, trekked for 10 days without hiking gear, food or maps into Chile.
Their efforts helped save the lives of 16 people and it is clear that, over 50 years on, the story still strikes a chord with those who hear it from the horse's mouth.
Speaking about Parrado's visit to camp, Ireland coach Simon Easterby said: "He's just a really inspirational figure in terms of what he and his team-mates went through in terrible conditions.
"A real inspiration and interesting to hear from someone who had been through all of that and still had the positivity to come out the other side and live a very good life."
'I don't think they could quite believe it'
Easterby continued: "It was really inspirational. Just someone you could relate to because of his rugby background.
"The team that he played with has a shamrock on the jersey that they play in and he obviously has a massive love and affiliation towards Ireland because of that."
Far removed from the line-out analyses and opposition scouting that are commonplace in squad gatherings, hearing Parrado tell his story understandably left an indelible impression on the Ireland players.
"Just shock I think," Easterby said when asked about the squad's response.
"I don't think they could quite believe it. Maybe they had seen the old film, or then there's another more recent one that's been made.
"But until you hear from the people actually involved in those experiences, you probably don't fully appreciate what they went through and how much they're relying on each other and how they were able to really work through some tough times and come out the other side.
"Obviously they lost a lot of friends and family along the way but it was a pretty inspiring story."
Easterby's reading of the squad's response was accurate, with full-back Hugo Keenan saying the players were "pretty blown away" by what they had learned.
"It's an amazing story of resilience, isn't it? It's mad to think about what he experienced," said Keenan.
"We've seen it in the movies but you get a completely new and more real sense of what they all went through on that journey.
"We're were taken aback by it. He spoke really well and it was a brilliant way to kick off the camp. To have him was brilliant.
"He told his story to us us and there were a few videos. There was a little Q&A at the end. We sat down and it went on for over an hour, but it didn't feel like it."