The unfettered naivety of it all. It is 20 years since I got my first cap against Australia but I remember it as distinctly as if it were yesterday. We were amateurs in every sense of the word. The game was flying full-force into professionalism and we were languishing in its back draft.
Heisenberg's Principle dictates that the act of observing a situation, changes it. In our case, we were somewhat oblivious to what was going on, so we may have been the exception that proves the rule; it would take a long time for change to happen in Irish rugby.
On that tour Australia had compiled a 30-page dossier on our touring party, a SWOT analysis ahead of its time. We had a half page on their team. We were worlds apart in terms of preparation.
This was before 24-hour sports coverage, the World Wide Web had just been invented and nobody was online. We only had a passing acquaintance with the team we were due to play.
On those foundations, there is little doubt as to the reasons we have not scaled World Cup heights. And yet with each group of players and each new international coach we have made significant strides. We have had setbacks too, but the improvements have been steadily upward for the last 15 years.
It brings us to this place and time and the unparalleled expectation of the Joe Schmidt era. I, like most the free world, expected South Africa to roll over an Irish team that was shorn of 17 players. With our leadership profile Ireland were sure to have a good performance, play well, and come up somewhat short.
But I forgot to factor in Joe's OCD. We presumed that his rookie centres would be terribly exposed and to be honest, they would have been if they had played to a normal pattern.
Instead, the game-plan was perfect to play against the machismo of South Africa. Rush defence, no passing, no risk. Payne and Henshaw played their opposition to a tee.
I was stunned by South Africa's lack of subtlety, their inability to adjust their play in the face of smarter opposition. Their way, as always, was to continue as they were but a bit harder, more aggressive, more direct. It didn't work, and it never does against a team that can resist the storm.
But Australia are a different proposition. They have plenty of nuance, artistry even. They play the space, not the man. And in their corner they have a Leinster man, one of the coaches of progression in Ireland over the last ten years.
Cheika is a winner and has tasted it in both hemispheres. He is not averse to a gamble on youth or experience. He is a fan of a tough pack but he wants his backs to play.
I was in Cardiff a few weeks ago for the Wales v Australia game and I was gobsmacked by the performance of Bernard Foley. The lateness at which he makes his decisions was a joy to see. His easy control of a game where defensively they were a bit at sea was astounding. He was calm and accurate and unflustered when things went a bit astray. He looked as if he has been playing at test level for years.
His play, and that of Israel Folau, are my big worries tomorrow. Their late runs and changes of direction can expose players not yet used to this level so I'm very happy to see Gordon Darcy lined up beside Henshaw. I would like Stuart Olding get a run but I'm happier for two young guys not to get thrown into this mixer.
Australia always seem to be in a game, even if they are being played off the park. They eke out a score, then a penalty and suddenly they are in touching distance again.
This is a far more mentally fatiguing test and one I would normally have a big fear over. But this time, 20 years on, I think we will know chapter and verse of what to expect.