It doesn't seem long since a baby-faced Joe Root first strode into the glare of international cricket.
It doesn't seem long since those first press conferences when, consumed by nerves, he blushed and blustered, or since Graeme Swann compared him to an "annoying little brother". It really isn't very long (it was at the end of the 2015 Ashes) since he couldn't control a fit of giggles when construing a double-entendre out of an innocent question about Stuart Broad's immaculate length.
But while he retains (lucky fellow) the fresh-faced look of a student who might still be asked for their ID in a bar, he has matured greatly in recent years and was the only realistic option for the vacancy of Test captain.
That is not to damn him with faint praise. It is to acknowledge that he has developed into an obvious leader for this young side. To acknowledge that he has, for a while, been England's best all-format batsman - might he be the best they have ever had in all three formats? - and that he has become a senior player, a vice-captain and a father.
He has retained a sense of fun - quite right, too, for it will help him maintain perspective on the days he is told he is a hero or a fool - but demonstrated a work ethic and hunger for success that has taken him, albeit briefly, to the very top of the Test batting rankings. Yes, by England standards, he is a young captain at 26 (Mike Atherton was 25), but the average age of an RAF pilot in 1940 was 20 and they managed rather well.
His challenges? He does not have, as Andrew Strauss and, for a while, Alastair Cook had, a top-class spinner on whom he can rely to give him control in the field. Until he does, success in Asia looks unlikely.
The time is looming, too, when England will have to look beyond James Anderson. Both Root's predecessors have been able to rely upon Anderson's control and skill for the bulk of their careers. It is no coincidence that he and Swann played defining roles in the Ashes success of 2010-11 and the India success of 2012. Such players are not easily replaced.
"The Root era promises the boldness of youth, the aggression of players brought up on T20 and encouraged to embrace their aggression. It promises likeability and entertainment"
But Root's most formidable opponent is perhaps England's own schedule. By expecting the team to play almost all year, to be away from home for more than six months at a time (if that sounds like hyperbole, check their schedule for the winter of 2017-18), England are asking a huge amount of those involved in all formats. For a young father with a history of back trouble, there must be dangers of burnout and exhaustion. Root will require careful management if he is to remain as productive as he might be into his 30s.
He inherits some tremendous assets, too. The reputations of Mike Brearley and Michael Vaughan as leaders were built, to a large part, on the presence of top allrounders in their side (Ian Botham and Andrew Flintoff at his best, respectively) and in Ben Stokes, Root has one to rival them. Indeed, his side is bursting with allrounders, which provides depth with bat and ball.
He also has, in Stuart Broad, a highly experienced attack leader who offers some security for LAA (life after Anderson), a middle-order that will relish his positive approach and a couple of promising players at the top of the order that have hinted - it is probably premature to claim more than that - they can solve the problems England have had there since the decline of Strauss.
It may well be that he proves a more natural fit with Trevor Bayliss, too. While Bayliss' aggression sometimes jarred with Cook's caution - most notably in England's attempts to bat for a draw in Vizakhapatnam - Root would seem to be of similarly positive mindset. Whether Test cricket really can be mastered with such an outlook remains to be seen, but it promises to be a lot of fun finding out. England look as if they are all on the same page now and an England side run by Root, Bayliss and Stokes promises very few dull moments.
The appointment of Stokes as vice-captain is arguably more revealing than the appointment of Root. England had other options for the vice-captaincy, including not appointing one at all. To give it to 25-year-old Stokes suggests they want the team to take on more of his traits: the aggression; the fight; the courage to trust to talent and respond to every punch with an even stronger counter-punch.
It's an appointment that makes a lot of sense, too. Stokes has expressed little enthusiasm for captaincy - he joked that captains had to be "boring like Cooky" when asked about it in India - but has the talent and force of personality that inspires. Like Cook and Broad and Anderson, he will prove a willing lieutenant to Root. There is no sign of unrest in Root's dressing room; some of his predecessors would have killed (a team-mate) for such harmony.
This is an era that promises the boldness of youth, the aggression of players brought up on T20 and encouraged to embrace their aggression. At a time when cricket in England is fighting for oxygen, it promises likeability and entertainment. These things may never have mattered more.
There is conflicting evidence for the effects of captaincy on an individual's batting. Cook, for example, made seven centuries in his first 11 Tests as captain (the first two as stand-in), while Steven Smith and Virat Kohli also appear to have taken to it with relish. Realistically, it seems the danger comes more from the long-term effects. Cook only made five more centuries in his final 48 Tests as captain; Root will need greater returns from him now.
His lack of captaincy experience - just four first-class games - is not ideal but it is a symptom of modernity. It is better, surely, that his ability as a batsman has kept him in the Test side almost constantly (he was dropped at the end of the 2013-14 Ashes) and that, unlike many predecessors, he should rarely be under pressure to justify his place as a batsman. For all the praise Brearley warrants as a captain, there is no chance he would win selection in this day and age. Besides, as Strauss said last week "playing in the middle and understanding the demands is more important than captaincy".
To be judged a success Root will probably have to lead England to the top of the rankings, win the Test Championship (if and when it is launched) and, most of all, keep beating Australia. But he won't be able to do it on his own: he will need county cricket to deliver him the players; the selectors to remain consistent; the coaches to help him create an environment which is at the same time relaxed and hardworking. And he'll need a supply of bowlers who can remain fit, gain lateral movement and bowl with control and pace. He will, in short, be reliant on many other cogs in the wheel if he is to prove a success.
But if he can retain the sense of fun that has characterised the best of England cricket in recent times, if he can retain the drive that has seen him and Stokes graduate from promising to excellent, if he can keep his back from seizing up and coax the best from his talented team, he has a great opportunity to build something quite exciting. It's a huge, demanding job without any guarantees of success, but Root is the right man for it.