What is the key position on a modern-day rugby team? Some would argue tighthead, others scrum-half, many out-half, perhaps the No 8?
In truth, rugby is probably the most inter-dependent team sport of all. The try scored at the corner after a free-flowing move following a scrum depends as much on the props anchoring that set-piece as it does the wing touching the ball down.
It was once a game for all shapes and sizes, but that description has, like almost everything else in the game, taken a battering in recent times.
Growing up in the No 10 shirt from U-9 at St Mary's, I guess I never really thought about the importance of the role other than the responsibility attached to goalkicking as I got older.
To me as an out-half, the flankers and scrum-half were always the most important players on my team. They looked after me in different ways.
The wing-forwards kept me safe from the evil equivalent on the other side, while the No 9 was the key to everything else.
Irish rugby has been particularly well served in the core sector down through the years. In the back-row and at half-back, we have at times been spoilt for choice - right now being a case in point.
All the way up through school, from U-9 to Senior, my scrum-half was Willie Ryan.
Willie switched to out-half to facilitate John Robbie when the two were competing for the No 9 shirt in Trinity, and together they masterminded a Leinster Senior Cup win in 1976 - a huge achievement. It was the university's first win since 1960 and indeed last outright success.
Willie was a dream to play with. The ultimate appreciation any ten can give his nine is to say he 'looked after' him - and Willie looked after me all the way through school.
Credit Roly Meates for turning him into a cup-winning out-half, but then with some players the ability to adjust is innate.
After school, John Moloney was, along with Shay Deering, my role model and hero. John and Shay were on the Mary's Senior Cup-winning side in 1966, when I was going into first year.
And my first senior cap for Ireland came alongside John against the Scots in 1978, when he took over the captaincy from Tom Grace.
John was one of seven scrum-halves I lined out alongside in green; the others were Colin Patterson, John Robbie, Robbie McGrath, Tony Doyle, Michael Bradley and Fergus Aherne.
Donal Canniffe was by a distance the stand-out scrum-half I played alongside in over a decade in red with Munster.
Prior to that, Jacques Fouroux and Gareth Edwards had set the standard for scrum-halves everywhere.
Fouroux was diminutive and while Edwards could hardly be described as big, he was much more compact, and he remains the most influential rugby player there's ever been.
Barry John used say to Gareth with tongue in cheek "you throw and I'll catch" but of course there was and is much more to a No 9's job than that.
The scrum-half primarily has to be able to pass well on both sides; he must have fast reactions with good judgement; he must have good communication skills and be vocal when it matters; he must be able to break and defend; and of course now more than ever he must be able to kick with precision.
The two traits I loved most in a scrum-half were a wrist-driven pass plus that ability to break, thereby keeping the opposition back-row honest and creating opportunities for others further out.
Kicking wasn't a major factor for No 9s in my day.
In recent years, we have had some top-quality scrum-halves in Ireland.
Eoin Reddan has just retired, while Peter Stringer is still playing.
Indeed if there has been a greater faux pas in the history of Munster rugby than prematurely releasing Stringer to the UK, then I don't know it.
Stringer was never the greatest breaker - he learnt early that given his lack of size, getting trapped meant loss of possession - but I can't think of a better passer of the ball, left or right, and that made him so influential.
When Reddan entered the action, the tempo always lifted instantly, whether with Leinster or Ireland. His was an all-action running game.
Stringer managed to quicken the tempo through that amazing pass alone. As an out-half I would have loved to have played alongside him.
As in almost every other position, the scrum-half has got bigger and stronger in the modern game. It began with players like Terry Holmes, Mike Phillips and the sadly departed Joost van der Westhuizen.
Conor Murray certainly has the advantage of physique on his side. He is a special scrum-half and an extraordinarily influential player.
He has all the traits listed above and while not a wristy passer a la Stringer or Patterson still has that sweeping action off either side that transfers the ball with maximum efficiency.
In addition he has the most amazing temperament I have come across in any top-class player at the heart of the action.
He is already the greatest scrum-half Ireland have ever had, and right up there with the best in the world.
It's no coincidence that Johnny Sexton and Paddy Jackson are producing some of the best rugby of their careers outside him, or that a rookie like Joey Carbery can step in as seamlessly on his Test debut as he did against the All Blacks in November.
Bear in mind that Murray is still only 27 with 56 caps, ten Test tries and a Lions tour to his name.
He ticks every box and while not (yet) wearing the captain's armband is every bit as influential as Paul O'Connell and Brian O'Driscoll were in their leadership pomp.
I still maintain that we will not appreciate the worth of Jamie Heaslip until he's gone but with Murray it's already clear for all to see.
Oh to have been born a few decades on!
Down weeks in the Six Nations can be frustrating for fans, forced to cast their eyes away from the gladiatorial arena of international rugby and reacquaint themselves with the provinces, who take a back seat for seven weeks each spring.