Mailer called ego 'the great word of the twentieth century... everything we have done, from monumental feats to nightmarish destruction has been a function of that extraordinary state of the psyche that enables us to declare that we are sure of ourselves when we are not'.
He was writing at the start of 1971, when the concept of ego was not as commonly used to pigeonhole great sportsmen. His was the first big piece, for example, that zeroed in on Ali's and examined it at length (everything Norman ever wrote involved tremendous length, because he was man of ego himself - it took one to know one).
Of course Ali was so hard to pin down, his life such a lightning rod, that his ego was some way down the list of things to write about.
Thirtysomething years later, ego has become the default position for writers and editors alike, because it's quick and easy shorthand for something far more complex. Of the thousands of words squandered on Kevin Pietersen this week, many have assembled themselves around ego. 'He's the kind of man who'd join the Navy so that the world could see him,' wrote one.
Pietersen has ego of course, but it is ego in its truest Freudian sense: a mediating force between desire and reason, a defence mechanism, a shell. Cricket's unique proposition to its batsmen - one chance and you're out - demands nothing less.
In a player of Pietersen's talent, ego is a finely balanced thing. The many well-documented rows and rejections over the early part of his career, his tenuous and unlikely path towards his current position and the fragility of a sportsman's life fuel his compulsive desire to control external forces and give his talent its greatest chance.
To hark back briefly to Bob Woolmer, in The Art and Science of Cricket, he writes: 'to review the raw, split-second data of what actually happens when batters execute a shot is to wonder how any batsman survives more than one delivery'. It's from this most basic point that any batsman starts out in cricket. To survive it mentally requires as much from the psyche as surviving physically does from the physiology.
Now imagine Pietersen's defining innings, the 158 at the Oval in '05. It would not have happened but for a magnificent decision from Billy Bowden on the first ball he faced, and a couple of dropped catches. By such slender threads, careers hang. It's enough to give anyone a few sleepless nights.
The most apparent parts of his character - the celeb wife, a love of the spotlight - cover a far less secure side governed by a natural conservatism. In one interview he admitted to going home after every shopping trip and immediately deducting the money he'd spent from his online bank account so he knew what was there. In another, asked what he thought of the naked pictures female fans sent him, he replied 'Dunno, it's your country, not mine'. Underneath the flamboyance lies a streak of moral rectitude: he may be a brash guy, but he's not a bad one.
The pivotal passage of that 158 came immediately after lunch, during a thrillingly quick spell from Brett Lee. 'I remember thinking, okay, it's him or me,' Pietersen said. Ego, real ego, kicked in, allowing his instinct full rein.
The stern decisiveness that's so necessary in batting does not work as well in real life, certainly as far as English officaldom goes. That mentality is a mystery to Pietersen. His mistakes this week were of misjudgment, of over-estimation, of immaturity and a bullish rejection of mediocrity.
What they were not were the signs of an uncontrollable ego. Batsmen, even those as brilliant as him, do not have them. Batting doesn't allow it. He competes in a fragile place, and he understands it perfectly. The way he reacts to the rest of life is just its consequence.
Pietersen is England's best player by a mile, and he deserves the same latitude afforded to Flintoff and Harmison. He hasn't received it yet.
'To declare that we are sure of ourselves when we are not'. That is ego. Norman had it exactly right, all those years ago.