The limits of labor

Funny story: There's this guy named Viktor Korchnoi...he came up in the late 40s and early 50s with the Spassky generation of bright young Soviet chessplayers. He got to grandmaster level around the time my dad graduated from college, and if we're honest about it, was probably the best player in the world or close to it in the mid-60s.
But what's odd about Korchnoi is he got to that level and just stayed there...for decades. Ten years after the 1960s peak (and a defection to the west), he was playing Karpov for the world title, and he was in contention for the title every cycle until the early-90s. According to the Chessmetrics website (which stopped updating in '04) his 20-year peak is comparable to Alekhine's or Smyslov's (both world champions). If there were a 30- or 40-year peak he would surely be the leader. And he is still there - he has now played rated games in eight separate decades. Here he is last year, aged 79, laying down an anti-positional smackdown on International Master Oliver Kurmann.
Korchnoi is sort of the anti-Bronstein, with whom he competes for the title of "greatest player to never be world champion," although when you look at his history it's hard to say he was an underachiever (there is no shame in not being quite as good as Karpov). His dogged style of play is often downright ugly.
But he vindicates the First Sea Lord's faith in effort and tenacity. He was never regarded as the most talented player of his generation, but he achieved everything except the summit. And here he is still, at a time when his contemporaries have retired or worse, hanging around the top few hundred or so players in the world, the lich-king of the chessboard.
Here is a story about him, too good not to repeat, secondhand from the chessgames forums:

I remember fondly one conversation I had a few years back with Boris Spassky. We were discussing 'THE' Victor Korchnoi ('Victor the Terrible' to many).
Boris and Victor had been bitter adversaries for more than 40 years at the time of this conversation, and they had played more than 60 times in official competitions..(including 2 candidates finals)... only Karpov can boast to have played Victor more times.
Boris, at one point, came up with the incredible statement that Korchnoi had every quality necessary to become world champion BUT lacked ONE very essential quality...and it was precisely this quality that prevented him from attaining chess' highest title.
I coaxed Boris on...He began to list Korchnoi's many qualities:
...Killer Instinct (nobody can even compare with Victor's 'gift')
...Phenomenal capacity to work (both on the board and off the board)
...Iron nerves (even with seconds left on the clock)
...Ability to Calculate (maybe only Fischer was better in this department)
...Tenacity and perseverance in Defense (unmatched by anyone)
...The ability to counterattack (unrivaled in chess history)
...Impeccable Technique (Flawless, even better than Capa's)
...Capacity to concentrate (unreal)
..Impervious to distractions during the game
...Brilliant understanding of strategy
...Superb tactician (only a few in history can compare with Victor)
...Possessing the most profound opening preparation of any GM of his generation
...Subtle Psychologist
...Super-human will to win (matched only by Fischer)
...Deep knowledge of all of his adversaries
...Enormous energy and self-discipline
Then Boris stopped, and just looked at me, begging for me to ask the question that needed to be asked....
I asked: 'But, Boris, what does Victor lack to become world champion?'
Boris' answer floored me:
''He has no chess talent !''
And then he roared with laughter...