Neil Francis: Without Joe Schmidt and Johnny Sexton, Ireland would have none of this success
Ireland's coach and his on-field general have put team in strong position to take series win
In January 49BC, Julius Caesar received instructions from the senate to leave Gaul and return home to Rome. He received explicit instructions not to travel with his army and that no legion should cross the Rubicon which was situated at Italy's northern border.
The future emperor decided to cross the Rubicon with the 13th legion - once he did, things would never be the same again. They could not simply cross back over again - the die was cast.
If Joe Schmidt leads his team to victory this Saturday - a win will be so much more than a series victory. A win has meaning on many levels, but it is a pronouncement that he can go anywhere in the world and win. That is significant.
Ireland should have won the series in South Africa in 2016 - but they were missing a seam of quality players and missed the opportunity when it was there for them. Paddy Jackson played well in the out-half position but if Jonathan Sexton had been on board, the series - I am convinced - would have been taken.
Ireland are by no means assured of a win this Saturday but they are in a strong position to do so because they have two like-minded individuals controlling their destiny - one on the field and one off it.
I would hazard a guess that if Joe Schmidt and Johnny Sexton were the subject of a psychological profile there would not be many differences on their respective profiles. The way they think, act and behave. Their relationship and extraordinarily successfully eight years together - it is I suggest not a coincidence that Ireland and Leinster have been so prosperous. It is worthy of some analysis.
When Sexton went to Racing for his two-year sabbatical, it was unprecedented the way Joe Schmidt went to France to get him back. Schmidt recognised what he had but this symbiotic relationship could not happen from a distance. Sexton should never have been let go in the first place but when Schmidt went over to France and persuaded Sexton to return - it showed just how compelling Schmidt's powers of reasoning and persuasion could be.
There is resentment in some quarters that Sexton was an exception to the rule - why was he alone granted this dispensation? The answer is obvious - look at the results. Sexton had the most lucrative contract extension at that time in French rugby history. All he had to do was sign and he would have been a wealthy man.
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I would have paid hard currency to hear the conversation - it might not have been as easy as some people think to coax Sexton back home.
There is a term used in Julius Caesar's time, 'Auctoritas'. There is no literal definition to the word but it tells you about a person of authority and his clout, influence and ability to rally support around his will or his way of thinking. You can be at the top of the food chain but unless you have power of command or have the ability to get things done, it is just a title.
Joe Schmidt has Auctoritas and the most influential thing he did was persuade Sexton to come home and be the conduit for the way Schmidt's team play - Sexton is the on-field extension of his own personality.
Schmidt's coaching philosophy has been called prescriptive and relies heavily on minute attention to detail - practically everything is done before the game.
Both Sexton and Schmidt are followers of the aggregation of marginal gains - a 1pc improvement in say half a dozen aspects of your performance on the field will yield a higher dividend than just a 6pc increase in one.
Other than pre-match training, the only other time that Schmidt can really directly influence his team is the 15 minutes at half-time which rarely fails to give his team a boost going into the third quarter. There is though only one person he can trust to control the game the way Schmidt wants it to be done. Sexton doesn't have to be the captain to be in charge - he just is.
Sexton's personality is, and has been, the key factor in Ireland's astonishing run of success - sometimes you think that his restlessness and his quest for perfection could be a difficulty for his team and team-mates; not many share that enthusiasm or drive.
Quite often a perfectionist can take it too far and quite often Sexton has been known to p**s off not only his Leinster and Ireland team-mates but his Lions team-mates as well.
I have always found a team functions better when there are one or two players in the side who do not permit sloppiness or loose execution or give players latitude who don't play the game-plan that was proposed by the leader.
Playing with Sexton provokes a response to play the best you can because that is what Sexton aims to do every time he takes the field.
They might give out about it sometimes but it forces the team to play better than if there was a less forceful player in the number 10 slot.
Sexton leads by precept and example. Not only is he an organiser and catalyst but his actions inspire. It takes a strong personality to lead the defensive line like Sexton. He has battlefield emotional intelligence and yet some of the things he does in the tackle are reckless to himself.
It straddles the border between inspiration and carelessness; either way, his team-mates are not blind to what he is prepared to do to protect his line - his bravery is contagious.
Sexton is pretty much the complete package. The only chink, and it becomes more pronounced the older you get, is the 'coachability' of your most important player. You have two very strong controlling personalities leading this team - it works as long as Sexton is still pliable and able to take instructions from his coach. That will end at some stage - hopefully not before next autumn in Japan.
If Schmidt and Sexton were not on board in 2014, 2015 and this season, Ireland would not have won the championship on those occasions. There are some high-quality people in management and in the playing roster but it would just not have come to pass without them.
A first series win on Australian soil in 39 years and the two controllers will have their team primed.
It is a natural progression but, like all things in sport that are worth doing, it will be decidedly difficult to achieve.
Australia are one of those sides that have great competitive instincts. It is they who now have to provoke a response in themselves to their loss in Melbourne. They will be encouraged that despite a game that Ireland dominated, they could still have won it at the death.
I think Michael Cheika's response will be for his team to be ultra-physical and play at a pace that Ireland may struggle to keep up with it for a full 80 minutes.
It is an intriguing match-up. Ireland's leaders wait to cross the west bank knowing that the perception of Ireland being able to beat anyone 'on a given day' could be dispelled, or their ability to win when they want to could bring them into a new territory. They will have crossed a threshold. The nation waits!