The strength in depth of this current F1 field is probably greater than at any time since the first couple of races of the 1982 season and I suspect that, over time, this will come to be seen as a golden age for the sport.
In Hamilton and Alonso, the sport has two drivers already established before this season as greats, and Button has now silenced the doubters to prove this season that he deserves to be ranked up there as well. Vettel is heading the same way and Webber is matching his team-mate blow for blow.
It is a heady mix, and it all came together to produce a stunning grand prix on the Circuit Gilles Villeneuve, so often the scene of drama and excitement.
The expected safety car periods did not materialise, despite plenty of wheel-banging and incident, but even so McLaren were proved right in their decision to qualify on the softer, option tyre, despite the scepticism it produced at the time.
The split strategies and rapid degradation of both the option and the harder 'prime' tyre created a race of changing fortunes and possibilities, and any one of those five drivers could have won had things gone slightly differently.
It was great to see Hamilton and Alonso at it hammer and tongs at the front again, reprising their great rivalry that started when they were team-mates at McLaren in 2007. And Button produced another understated, classy, skilful race - rapier to their broadsword in the manner of the great Alain Prost - to ease up the field as the race progressed.
Red Bull split their strategies - putting Webber on the prime tyre at his first pit stop, so he would run the difficult option in the final stint, and Vettel on the option, getting it out of the way - in the hope that at least one of them would get it right.
But it did not work out for them.
Vettel was right in contention until having to back off to nurse his gearbox in the closing laps, and the prime tyres went off too quickly for Webber's strategy to work out. When teams go into a race knowing they are going to have to 'wing it' on strategy because they have no idea how the tyres will behave, this is the sort of thing that can happen.
Vettel follows his car back to the pits after the race. Photo: AP.
Team boss Christian Horner said Red Bull were actually pleased to have come away with fourth and fifth places.
"We shouldn't be too disappointed," he said. "We always knew this race was going to favour the McLarens. We were actually more competitive here than we expected to be, which I think is an encouraging sign."
Horner may be right to point out that there are circuits coming up that will suit Red Bull better - and certainly, as things stand at the moment, they would be expected to walk the British and Belgian Grands Prix, for example.
Two races ago, Webber had taken two dominant victories at tracks as different as Barcelona and Monaco, the second a one-two with Vettel. And they should have had another in Turkey two weeks ago only for the two drivers to have their notorious collision.
But all of a sudden things do not look quite so great for Red Bull.
McLaren are getting stronger and stronger - and will go to Valencia as favourites because that track, like Montreal, is predominantly slow corners and straights. And Ferrari, back on form here, are due a major aerodynamic upgrade for that event.
Increasingly it looks as if Red Bull, still encountering reliability issues, may suffer for their scrappy start to the season, which delivered only three wins despite either Webber or Vettel being on pole position for all the first seven races.
A leading member of a rival team said to me this weekend: "Red Bull may live to regret that. You've got to deliver the wins when you're strong because sooner or later you'll get caught."
As an example, he pointed to Alonso's championship winning year for Renault in 2006, when the Spaniard built a huge lead with a dominant car at the start of the season but ended up fighting a rearguard battle against Ferrari and Michael Schumacher.
A large part of Red Bull's aerodynamic performance advantage so far this season is now believed by rival engineers to come from the design of the rear of the car.
They have sited their exhaust exits low down, blowing into the 'coke-bottle' shape of the bodywork and through slots in the floor of the car into the diffuser. I'm told by aerodynamicists from Red Bull's rivals that this is worth at least half a second a lap.
Ferrari are introducing their version of the design in Valencia, with McLaren aiming for the next race at Silverstone or possibly two weeks later in Germany. Renault, who are not far behind, have one due soon, too.
In Canada and before that in Turkey, McLaren did what Red Bull have too often not - delivering a win when they were strong, to add to Button's two opportunist wins from earlier in the season. They and Ferrari are closing in and after Canada Red Bull are now chasing the championship lead rather than setting the pace.
In that sense, the Canadian GP was a microcosm of the title battle to come - any one of five drivers could win it and watching them battle it out has the potential to produce a classic season.
Source : http://www.bbc.co.uk/blogs/andrewbenson/2010/06/hamilton_proves_up_to_his_ulti.html