Mark Boucher has no 'Off' button. He is always on, always competitive, always staring a hole in his next challenge, always expecting to win, or to die trying.
"Hot in this town, isn't it?" he was asked after the fourth day's play in the Boxing Day Test against India in Durban. "Yes, especially now that the sun is out," Boucher bristled with reference to the fact that bad light, allegedly, had hastened the close after India lurched to 38 for 2 in search of 354, a target that proved 174 runs too far away.
This view of life from the sharp end is not some facade Boucher has manufactured to help him deal with the world. This is just the way he is, always has been and will be until he fights his last battle. He really is what he seems to be as he struts onto the field: one hard bastard.
At Centurion in the first Test against Pakistan, Boucher will become something else - just the fourth South African to earn 100 Test caps.
The only other South Africans in this exclusive club are Shaun Pollock, Jacques Kallis and Gary Kirsten, all of them bona fide greats in this country's cricket history. To earn membership to this pantheon will mean much to Boucher, who even after the thrills and spills of nine years as an international player retains a schoolboyish pride in the honours that come with excelling at his chosen profession.
And how he has excelled. Boucher's 3721 Test runs and his 380 dismissals do not tell a smidgeon of the story. The fact that he played his first 75 Tests consecutively - a South African record - takes us closer to the truth.
For an age his selection was a no-brainer, a fact waiting to happen. Then, three years ago, he was dropped. Perhaps he had begun to take his place for granted, which if that was true was an attitude as unhealthy as it would have been understandable due to the lack of a genuine rival.
But those dark days have passed and Boucher is once more a committed member of the side and an example to anyone for what it takes to turn talent, skill, determination and temperament into success.
In fact, the only 'keeper more deadly than Boucher in Test cricket is Ian Healy, who retired with 395 dismissals. In one-day cricket, Adam Gilchrist wears the crown with 406 victims while Boucher has 337. The thing is, Healy played 119 Tests, while Gilchrist has racked up 247 one-dayers to Boucher's 228.
Will Boucher become the most successful stumper the game has yet seen? At 30 and still without a serious contender to replace him in the South African team, he surely has several years left to stake his claim.
To those who knew little of Boucher when Dave Richardson injured a finger in Pakistan in 1997, none of the above would have seemed likely.
Indeed, as Boucher stood in his typical teenager's bedroom in East London and packed furiously for Sheikhupura, even those he had already impressed must have wondered whether he would make the grade.
He was then, believe it or not, a quiet, shy, youngster who seemed more comfortable studying the ground in front of him than talking to the press. When he did look up to answer a question, he peered through a sheltering fringe and spoke as if he was afraid of waking a baby.
Boucher has come a long way since then. But even in those far off days he had the stare, the corrosive glare that told all who saw it that he knew he was bound for the top.
The shyness is long gone, as is the fringe. However, the glare has remained constant. It must: it is Boucher's 'On' button.