It's obvious, but easily underestimated, that in politics judgement and temperament are key. Together with character, with which they're often entwined, they are probably more important than high intelligence, or low cunning.
We just need to look at the federal scene today.
Barnaby Joyce provides the current case study about the importance of judgement or in his instance, lack or it. Here is a career, so carefully built, dramatically torn down by his own hand.
And as for temperament, we have the contrasting examples of Mathias Cormann and Greg Hunt, of whom more later.
Mr Joyce burst onto the political scene in 2005 as a larger-than-life high profile Nationals senator. Because of tight numbers, he started with disproportionate power; for his Coalition peers and betters, he was a headache.
But he had charisma out in the bush, and ambition, and he set his sights on becoming Nationals leader, eventually adopting (mostly) the discipline needed to get there. When he reached the deputy prime ministership he began well, and his party outperformed the Liberals at the 2016 election.
But soon after, his private life became complicated, with his staffer Vikki Campion the new woman in his life.
Ms Campion says in Sunday's interview on Seven, "you can't help who you fall in love with". That may or may not be true, but you can manage the implications.Give us all a break!
A public figure can separate the work and private parts of their lives. Mr Joyce let the two merge messily, as Ms Campion shifted to colleagues' offices. With this failure of judgment, his fall began.
Now we have the paid interview. You only need political instinct, not even judgement, to know it's unacceptable.
Then, when things became hot, Mr Joyce this week took leave. Leader of the House Christopher Pyne said Mr Joyce had a doctor's sick- leave certificate, "and any other person in a workplace who produced such a certificate would get the same kind of leave".
Give us all a break! An MP gets a reported $150,000 for a "tell all" interview, and when people are critical he goes on stress leave.
To people away from politics, coping with serious stresses often not of their own making, this saga just comes across as self-indulgence.Joyce will have a big rebuilding job
Now there is speculation about Mr Joyce's future — will he, should he, stay on in his seat of New England?
This ought to be resolved quickly, for Mr Joyce's own sake, and that of the Nationals, who don't want to risk the emergence of a new strong independent, remembering that Tony Windsor grabbed and held this electorate for many years.
If Joyce wants to stay, he'll have a big rebuilding job, locally and in Canberra. If — and it would probably be the more sensible course — he feels it would be better to strike out into another career, he should announce that decision without delay (while of course remaining in place until the election).Street angel, house devil
Probably no-one would be surprised to hear of a few expletives from Mr Joyce, but this week's News Corp story that Greg Hunt had sworn at the mayor of the Northern Territory town of Katherine, Fay Miller, in a private meeting last year, telling her she needed to "f***ing get over" herself, would have raised eyebrows among those who see the very reasonable-sounding Health Minister on TV.
Mr Hunt only apologised to Ms Miller — who'd been leading a delegation from the town to discuss a health package following contamination from RAAF Base Tindal — when the story was about to break.
Mr Hunt's temperament is of the "street angel, house devil" type; he is known for private outbursts of temper, and has now been rather dramatically "outed".
In Question Time on Thursday, pursued by the Opposition, he also admitted that he'd been subject of a complaint after what he described as a "strong discussion" with a former health department secretary (Martin Bowles).
He told Parliament: "The Prime Minister himself raised it and asked that I speak with the secretary of Prime Minister and Cabinet."
The nature of Mr Hunt's behaviour can be judged by the fact that departmental secretaries — robust characters, for the most part — don't usually complain upwards, to the head of the Prime Minister's department, when their Ministers have "strong discussions" with them.
Colleagues might recall such incidents, if Mr Hunt in years to come eyes his party's deputy leadership — a position that ideally requires an even temperament.Corman displays patience and good humour
Fortunately for the Government, Mr Hunt isn't in the sort of position occupied by Senate leader Mathias Cormann, who has to manage relationships and negotiate in perennially-testing circumstances.
Mr Cormann has had a few heated clashes with opponents, especially recently with Labor's Senate leader Penny Wong, but he manages political conflict in a civilised, quite respectful way. In dealing with a Senate crossbench packed with volatile and unpredictable characters surfing atop inflated egos, Senator Cormann displays inexhaustible patience and general good humour.
Beyond judgement and temperament, there is another quality that is crucial in politics: character.
The voters are like sniffer dogs when it comes to character — if that hadn't been the case Mark Latham might have won the 2004 election.
For years, the Government has been on a constant mission to fan doubts about Bill Shorten's character. It knows that if such an attack is effective, it can be lethal for a leader's chances.
That was in part behind the Abbott government establishing the royal commission into trade unions. And it's why Michaelia Cash set the Registered Organisations Commission onto the 2005 $100,000 Australian Workers Union donation to GetUp, when Mr Shorten was union secretary. But as we saw this week, the donation affair has so far inflicted more pain on the Government than on Mr Shorten.
We know from the polls the public don't warm to the Opposition Leader. So far, however, Labor's two-party lead indicates people haven't concluded that he is not fit to rule. Mr Shorten hasn't failed the character test, but he hasn't entirely passed it yet, either.
Michelle Grattan is a professorial fellow at the University of Canberra and chief political correspondent at The Conversation, where this article appeared.