The mental health of a professional sportsman should ideally be nobody's business but his own.
Ronnie O'Sullivan is entitled to this courtesy too but his professional fortunes have been so intertwined with his personal well-being that it has become a matter of public knowledge.
He doesn't play a team sport in which issues of this nature can be more easily kept under wraps. He plays an individual sport where it's harder to hide. And, in addition, a sport which punishes errors of such tiny margins it borders on the psychologically sadistic. It offers no comfort to the fragile mind.
The greatest of snooker's practitioners, from Davis to Hendry to John Higgins, were mentally made of granite. O'Sullivan is a better player than any of them. He is beyond brilliant. Hendry took the business of winning to a new level. O'Sullivan took the game itself to a new frontier. The same could be said of Jimmy White, who also performed newly-minted feats on the green baize.
But unlike White, Ronnie belongs in the company of Davis and Hendry as a winner too. His greatest personal achievement, perhaps, was to convert that extravagant natural flamboyance into the hard currency of titles and trophies.
He is a classic archetype: the genius with the self-destruct impulse. When he won the UK Championship in 1993 he became the youngest ever winner of a world-ranking tournament. A year later, he publicly threatened to quit the game. He was 18. He's been threatening to quit it ever since, tormented by its treacheries, pummelled by his mood swings, depression and, at one time, his addiction problems.
Then there was the almost narcissistic commitment to style and beauty. He believed the game could be an art form if it was played with the requisite style. He wanted to play it with the requisite style. He wanted to be its George Best, Tiger Woods, Sugar Ray Leonard, Bruce Lee. He was a big fan of Bruce Lee.
But all that style would be a hollow thing without the substance of achievement. O'Sullivan made a lot of people wonder about his capacity for hard combat against formidable opponents, especially under the mind-bending pressure of the World Championships. He had the talent to win world titles, undoubtedly; but it also required implacable discipline and concentration.
The talent and the discipline seemed poles apart many times during his career. But in 2001 they converged. At the Crucible Theatre that year he was unusually calm and self-contained. His vast gift was harnessed and funnelled into the ultimate test of mental strength. He beat Higgins, then the most formidable of them all, in the final. It was a joy and a relief to behold, not just because of his troubled life and times, but also because society has a habit of punishing the gifted. It can be very unforgiving of the artist maverick. But he came through; and in that moment he was vindicated.
Since then O'Sullivan's prospects at every World Championship, at every tournament he enters, have been analysed almost entirely in personal terms. His form as a professional player is never relevant. He is measured by his emotional state, his psychological well-being. No one considers it prurient to talk about him publicly in this way. And in fact he has himself spoken openly many times about the travails in his head, and indeed the torments of the game.
He won subsequent world titles in 2004 and 2008. The long gaps confirm the struggle he has aligning his gift to a quiet mind. As recently as last week he spoke about "collapsing" in a hotel room during a tournament last December. The travelling, the loneliness on the circuit, wears him down. He said it endangers his health. He has also been engaged in a protracted custody battle for his two children, which has taken its toll too.
It has been a pleasant surprise therefore to see him so calm and focused at the Crucible this year. He has been working with a psychiatrist who specialises in sports performance. He has rediscovered the mindset he had in '01, '04 and '08. And he has played some devastating snooker. He has gone Bruce Lee on it. The shots have flowed in torrents. He has unleashed the full repertoire of stuns and spins and screws and cannons. The speed has at times been breathtaking.
He reeled off nine frames in a row against Mark Williams, including a 128 clearance of such virtuosity it prompted a standing ovation from the audience. He reeled off six in a row against Neil Robertson in the quarter-final, and another six on the spin against Matthew Stevens last Friday. That session against Stevens included two tons, bringing his career centuries to 678.
"I haven't seen him this happy for a long time," said Terry Griffiths on commentary during the Robertson match. "There's a peacefulness about him around the table. You can see it."
Asked at a press conference about his "serenity" this fortnight, O'Sullivan replied: "Yeah, it's a bit late though, isn't it? I could've done with being like this 15 years ago." Typical Ronnie -- always down on himself.
But he has endured. He is tougher than he led us to believe. For all his troubles, and despite his long love-hate affair with the game, he has stayed the course. At the age of 36 the great stylist, the brittle diva, has become, of all things, a hardened survivor.