They are the sounding boards for the ideas - good, bad but never indifferent, passed down from on high. They are often the first and almost always the last ports of call for advice before crucial decisions are made. They are the jesters at the foot of the throne. They are the ones who can tell the Emperor he has no clothes.
They are the communication channels between those who lead and those who can only dream of leading. Their desks guard the door to the inner sanctum. They control who enters - and for how long. They control the phones. They control the flow of information. They control who sees what. They are the eyes and ears of their master or mistress.
Their job is to spot trouble before anyone else notices any trouble to spot. And then deal with it. Quickly. They do not court publicity even though those in the publicity business might try to court them. They never upstage their boss, their relationship with whom is one of absolute mutual trust. If and when that commodity is exhausted and all trust is gone, so are they.
''They'' are chiefs of staff who run the offices of respective party leaders at Parliament and who are the largely unseen, unheralded right-hand men and women upon whom the country's senior politicians depend utterly.
It is into this all-consuming and absolutely pivotal role in the Labour leader's office that Matt McCarten has now been thrust. Not to do the donkey work of office administration, but to offer strategic and tactical advice as to how David Cunliffe embarks on the Sisyphean task of getting the better of what Mr McCarten calls the ''phenomenon'' of John Key.
So far the narrative has been more about Mr McCarten and less about how he might actually do something to help Labour close at least some of that vast gap in the polls in the run-up to the election later this year.
The appointment was an audacious move on Mr Cunliffe's part, He has taken a big punt on would-be Labour voters swallowing hard and accepting that the ex-Alliance cuckoo be allowed into the Labour nest for the common good of the centre-left.
But it looks like there is going to be a price to pay. Judging from comments posted on the Herald's website, some voters are already reassessing whether they will give Labour their vote.
It is still early days. In this instance, Mr McCarten is also better judged by his results, rather than his ideology.
Nevertheless, John Key's informal scare campaign, which is designed to frighten voters off the idea of Labour-Greens coalition government, has been given a whole new dimension.
The prime minister wasted no time in typecasting Mr McCarten as someone from the ''hard left''. He predicted the appointment would see a change in Labour's tone and the major Opposition party would become much more aligned with the Greens.
That is not going to happen. But this is all about Mr Key creating perceptions, namely that Mr McCarten's appointment is further evidence of Labour ''lurching'' to the left.
That perception is oddly enough somewhat reinforced every time Mr Cunliffe seeks to challenge it.
He insists he is not moving Labour leftwards. Yet those on the party's left have cheered and applauded everything he has said about the direction he intends taking Labour under his leadership.
That has some of his colleagues worried that the strong rhetoric he wheels out for that audience risks alienating a far bigger and more crucial one in the political centre.
Labour must win votes in the middle ground as well as among low-income earners struggling to make ends meet. The concern is that Mr Cunliffe will have to shift his focus back to the centre at some point which would have those on the left furiously slamming him as insincere and a phoney, while those in the centre would simply view his sudden and belated efforts to woo them as plain desperation.
There are deeper forces at work here which should be key determinants of where Mr Cunliffe should position Labour. But he appears to have taken little cognisance, instead leaving doubt and ambiguity as to where Labour stands on the spectrum even if Mr Cunliffe, to his credit, is much clearer about what Labour stands for.
However, at some point, Mr Cunliffe is going to have to confront what is for Labour an unpalatable fact of political life in New Zealand.
It is something Helen Clark well understood and something which underpinned her strategic thinking as leader and prompted her to position Labour as close as possible to the centre.
Labour's humiliation in the 1975 general election taught her a vital lesson - never underestimate the deeply conservative disposition of the great bulk of New Zealand voters.
It takes them a long time to get sick of National governments. Apart from Miss Clark's administration, voters' flirtation with Labour can be remarkably short-lived. That has been the pattern since World War 2. There has been nothing in this election year to alter that assessment. Instead, there is much to reinforce it.
That conservative streak running through the electorate was why she shut the Alliance out of the finance portfolio completely when she won the 1999 election.
In the end, she could not stop that conservatism killing her administration. That conservatism came in different clothing - namely voter antipathy towards so-called political correctness.
So far, Mr Cunliffe has been able to straddle both the centre and centre-left parts of the political spectrum to some degree. The ''baby bonus'' policy catered to both the poor and the reasonably well-off. The setting up of a state-owned insurance company was not a million miles from the kind of things the last minority Labour government did.
Where Mr Cunliffe has major problems with voters is on the trust and sincerity front, in part because they do not know what to make of him. Perhaps unwittingly, Mr McCarten likewise made mention in one radio interview of his uncertainty at one point as to whether Mr Cunliffe was for real.
January's 3News-Reid Research poll had Mr Cunliffe trailing his predecessor, David Shearer, in terms of substance over style, being down to earth and not talking down to people.
Mr McCarten has work to do on the credibility front.
And if all of that was not enough, there is a showstopper: how the heck do you sell a capital gains tax in a country where property is king.
- John Armstrong is The New Zealand Herald political correspondent.
