Why ageing Hamilton needs to dig deeper than ever

History bestows on us perspective; it permits us to slice and dice events into neat and easily-labelled compartments. The history of grand prix racing is no exception, wafting gracefully from clearly-defined era to clearly-defined era.

But that perspective also irons out the kinks, the blemishes, the mucky reality that makes what seems starkly obvious in retrospect invisible in real time. "Progress isn't always a straight line or a smooth path," as former US president Barack Obama puts it.

No matter how great things seem to be for Lewis Hamilton right now, with pre-season testing setting him up as world championship favourite yet again, there will be a time when he must face down the forces of history. And it could happen this year.

This is unquestionably Hamilton's era. You could call it the Mercedes era if you like, but it is drivers, above all, who define these pockets of time in the minds of the fans. With three world championships in four seasons, and gunning for a fifth overall this year, this is Hamilton's world and everyone else in F1 is just living in it.

There seems no end to it. Five, six - even the magic seven titles - seem inevitable. But there can never be certainty, because if there's one thing we can be sure of it's that, if the times are not a changing now, they will be very soon.

Grand Prix racing's eras are generally short and, for the victors, very sweet. Admittedly, there are some sketchy transitions, but you can bound back almost a quarter of a century in a few easy steps - the Hamilton/Mercedes era, the Sebastian Vettel/Red Bull era, the Michael Schumacher era (interrupted by the Fernando Alonso era that never quite came to pass).

This connects us to one of the most sudden and horrific transitions of all, that fateful day on 1 May 1994 when the Ayrton Senna era came to a tragic end and Schumacher picked up the baton.

That season started with everyone wondering just how many world championships Senna would win after moving to Williams - four, five, six, even the seven that history now tells us might have been possible based on the team's Renault-powered performance level? The point is, what we thought was going to happen did not. History blindsides the best of us (just ask the aforementioned Obama...)

What makes what Mercedes has achieved so remarkable in recent years is that it has become the first team to maintain its supremacy through a major aerodynamic rule change, so right now the natural assumption is that Hamilton will continue to win titles until the next big rule change creates an opportunity for a shift in the balance of power. But you know how the saying goes about assumptions.

Hamilton has been talking up the possibility of a three-way inter-team fight at the front between Mercedes, Ferrari and Red Bull. He might be doing that out of a desire to manage expectations, a sincere belief things will be nip and tuck this year, or just to build up excitement for the season. But having gone five seasons between his first title and his second, he knows how easy it is to be knocked off your perch.

"This year is going to be exciting, because last year there was a big difference between teams in the beginning and they got closer," Hamilton said last week. "But this year, it starts this close and then it's going to overlap, and separate, and overlap during the year as people are developing.

"I think Red Bull are the fastest at the moment, potentially. They have some sort of upgrade coming, of some magnitude, two-to-four tenths or something like that."

And there's your mechanism for change. Hamilton has only recently turned 33, and with his new Mercedes deal supposedly imminent, he's at the top of his game - so why shouldn't he stay on top? Well, partly because he's dependent on the machinery still being up to it.

But there's a more important factor - good as Hamilton is, he is not head and shoulders above his competition. It's impossible for any driver to be that in the way that it was in, say, Juan Manuel Fangio's time. Standards are simply too high, the differences too small. Modern elite sport is about aggregation of marginal gains. Hamilton is a great driver, but he's not strides ahead of his pursuers.

Which brings us to Max Verstappen. If Red Bull is up to the job of fighting for the world championship rather than just the odd win here and there, held back by a Renault engine package that's 40-50bhp down on Mercedes, then he is the anointed one.

Remarkably, Verstappen is not 21 until September and has already gone through the mandatory early stages of being an upstart disruptive force and then emerging as a feather-ruffling winner. He's now an established top gun, and provided he can stand up to the intensity of a season-long championship battle, he's got what it takes to win a title. There's the same magic about Verstappen that there was about Hamilton at the corresponding time in his career.

The cliche that age is but a number is a tired one, but when it comes to era-change narratives it's irresistible. Verstappen is the young, wild upstart who is shaking up grand prix racing - just as Hamilton himself was a decade ago.

Hamilton is now the elder statesman, a driver whose place among the all-time greats would be guaranteed even if he decided to pack up and quit tomorrow. He's still got plenty of years left in him, but he's in the age range when era-defining drivers have a habit of handing over to the next generation. It takes a combination of luck, circumstances, ability and sheer determination to hang on.

Suppose you've climbed Everest - what motivates you to climb it a second, third, fourth or fifth time? The most determined will retain their enthusiasm, but nobody escapes the law of diminishing returns forever

Jim Clark was 32 when he died in 1968, Alain Prost was 33 when Ayrton Senna joined him at McLaren in 1988, Jackie Stewart quit and Senna lost his life at 34, while Michael Schumacher was 36 when he was toppled by Fernando Alonso. The mid-30s are a difficult age for any dominant force, and you don't always get to relinquish your position as gracefully as Stewart even without tragedy intervening. Regardless of the variety of historic mechanisms for change, the fact they happened are a warning to Hamilton.

If Verstappen is able to fight for the drivers' championship this year, it will be a gruelling test for both him and Hamilton.

Hamilton has never come up against a driver quite like Verstappen on equal terms. Last year, he proved he had Vettel licked in terms of mental strength and turned in the most formidable season of his grand prix career. But Verstappen is something different.

As for Verstappen, how does a driver barely out of his teens with three grand prix victories to his name find a way to beat a foe who has achieved so much?

This could set the stage for a season for the ages. If the Red Bull is in the mix, there's every chance that Verstappen's formidable racecraft will be the key to success. If the Mercedes qualifying advantage remains, he could often find himself without the advantage of track position but a car that is equal to, or even slightly ahead of, Mercedes on race pace. Turning that around race after race will require something special. This will test Verstappen, and his ability to judge when to attack and when to consolidate.

As for Hamilton, it will be a test of his desire. No driver has infinite reserves of that and that's one of the key factors in the battles that decide if an era is extended or ended. You might think such resource is infinite, but suppose you've just climbed Mount Everest - what motivates you to climb it a second, third, fourth, fifth time? The most determined will retain much or all of their virgin enthusiasm, but nobody escapes the law of diminishing returns forever. Hamilton could stay at the top of his game for five or more years - but he will have to demonstrate a tight grip to hang on to his current position.

That's what suggests this season could be part of a far bigger story. Hamilton still appears to be fully determined and motivated, and increasingly makes comments suggesting he wants to be challenged and pushed. He would love to see off Verstappen in a straight fight. If Verstappen does go on to become the next era-defining driver that's probably the last box Hamilton can tick in the list of greatness. And there's a feeling that this a fight Hamilton will eventually have to take on, whether it's this year, or beyond.

As for Verstappen, he's portrayed as a man in a hurry and will unquestionably try and convert any slender chance of a title into a serious push. But he also knows how far he has come in a short time and believe it or not there is also some patience there - and that might be his biggest weapon in such a fight. Knowing he doesn't have to win might just make him better equipped to do so. He will be a formidable rival.

Then there are the wildcards. At Ferrari, Sebastian Vettel can re-stake his own claim to extending his era by winning a championship for grand prix racing's most legendary team. He needs to show he can avoid the red mist moments that blighted him last year and deliver the level of serenity of his Red Bull pomp.

At Red Bull, Daniel Ricciardo risks being caught between two eras and, at 28, knows he needs to be winning world championships. He's a classy, classical racing driver capable of great speed and remarkable feats of overtaking - his challenge is to rise to the challenge of Verstappen in the same machinery. He can do it, but it will require him to push himself to another level.

Right now, a fifth Hamilton world championship seems most likely. But that's the thing with sport - it's unpredictable, and all empires eventually fall. It's just a question of when

Then there's Valtteri Bottas, whose shot at the big time could come to an end with his current Mercedes deal at the end of the year. He needs to show he's capable of winning more consistency up against a true great like Hamilton and push his team-mate hard - what better motivation could there be than that? Cometh the hour, cometh the man.

We also have Kimi Raikkonen, who must roll back the years and show he's more than the stoolpigeon he's been for most of his second Ferrari career. He's the least likely of the six drivers in the top six teams to make an impact - but what a story it would be if he could defy all rational expectations?

And the real long shot? A driver whose big successes came even before Raikkonen's - Fernando Alonso. McLaren has got some big steps to take to get into the mix at the front (although should have the biggest step of anyone in Melbourne if its expectations are met). Alonso's stalled era started with back-to-back titles in 2005 and '06 but then lost momentum. That elusive third title could also reshape how history sees this period of grand prix racing, but 2018 is surely too early for the team if not the ageing driver.

Any of those drivers with the means, motive and opportunity will be grasping at Hamilton's crown. Right now, a fifth Hamilton world championship seems most likely. But that's the thing with sport - it is unpredictable. It is just a question of when.

So whatever happens, 2018 will be a significant and gripping season. If Hamilton wins, he's holding back the tide of the standard-raising youth while extending his ride of the crest of a wave that might take him to five, six, seven world titles. But if Verstappen can win, or even give him a good fight, it will be something else entirely. And that challenge could force Hamilton to raise his game still further.

Ultimately, 'might' is the key word here. History will see what is about to happen, as clear as day. But we won't, and that's what makes what could happen so thrilling.

All empires eventually fall. The only question is how long the emperor can keep the inevitable at bay.