With the jury selected in the Conrad Black trial, it's worth looking at why some corporate leaders go off the rails? Is it greed? Arrogance?

Tom Walker's thought-provoking piece in the Atlanta Constitution Journal is worth checking out.

As Walker says, it might boil down to their belief that the rules don't apply to them. They're invincible, y'see.

And Conrad Black, of course, would be right up there although as The Guardian's Andrew Clark noticed on Day One in the court-room, the air of invincibility is starting to slip.

Still, that invincibility has been very much part of Black's character. As Black's biographer George Tombs told Clark: "At some level, he's still asking the same question as he was when he was seven or eight - who am I? I'm not sure if it's narcissism so much as a compulsive need to link himself to historical greatness."

And this is where it becomes a problem: the same sorts of people are also hard-headed and determined, qualities that made them successful in the first place. The invincibility, therefore, is the dark side of those strong points that the market just loves.