OPINION: Nowhere else does the word rejuvenation strike such fear into the heart as in politics.
There is a "for whom the bells toll" quality to the word, which to politicians is synonymous with less-comforting terminology like purge, dead wood and old guard.
Rejuvenation of political parties rarely happens without a word in the ear, blood on the floor and a row of colleagues lined up behind your back ready to plunge the knife in.
The fact then that National has managed to retire seven of its MPs so far, with more rumoured to be on the way, and with not even a hint of a backbench revolt, is a truly remarkable feat.
It could of course be a noble gesture by those MPs to make way for new blood, but a rollcall of those who've so far announced they are calling it quits suggests otherwise.
Phil Heatley and Kate Wilkinson were both dumped from Cabinet by Prime Minister John Key in a fashion that gave a pretty clear indication there was no future for them in politics.
Cam Calder, Chris Auchinvole and Paul Hutchison have cooled their heels on the back benches for long enough to know that their stars are never going to rise.
Katrina Shanks has been similarly low-profile. But she may also have tired of standing in a seat where she was under orders to throw the race so Peter Dunne could be assured of returning to Parliament.
The only real surprise so far among National's "retirees" has been Internal Affairs Minister Chris Tremain, who seemed to have a reasonable expectation of promotion down the track.
Senior Nats are signalling, meanwhile, that there are more on the way.
Apart from the rumoured move to the list by Murray McCully from his safe East Coast Bays seat, the word is that "one or two" more retirements are yet to be announced.
That suggests there could be as many as a dozen MPs collecting silver platters as they head out the door.
It's tempting to think that maybe these MPs know something we don't.
The collective urge among longer serving MPs to move on rarely strikes until a government is on its way out and panic sets in over the prospect of being flung back into Opposition.
On purely financial grounds there is no real reason for MPs to face the prospect of Opposition with such fear and loathing. A backbencher's pay remains the same no matter which side of the fence you are on.
But after a couple of terms in Government, hubris inevitably sets in.
Government MPs get used to sneering at their opponents as a bunch of no-hopers who don't have a clue.
The prospect of the roles being reversed and watching their opponents preen from the Government benches is too much for some MPs to stomach.
There is also the fact that the number of jobs calling for "ex-MP" on the CV are slim, so it helps to get a head-start on any colleagues who may find themselves forcibly retired by the voters.
However, at this point in the electoral cycle there is no reason for the Nats to feel particularly blue about their prospects of eking out another term.
This suggests the slew of departures is more by the design of National Party HQ than accident.
One of former Labour prime minister Helen Clark's biggest mistakes in Government was seen as her failure to rejuvenate Labour's ranks.
The party list was at one stage a blatant tool for buying caucus discipline and unity, in that it reserved all the winnable slots for sitting MPs.
But when the mood for change set in Labour was unable to turn that around by putting a fresh face on fresh ideas.
John Key watched and learned.
In part, Clark's imperative to keep peace was driven by Labour's previous bloody factionalism, but it was also in response to National's own messy civil war during the early 2000s when former party president Michelle Boag famously embarked on a purge of National's "dead wood".
The purge caused angst not just among the MPs shoulder-barged out of Parliament - many of their colleagues were dismayed at the undignified way in which some long-serving Nats had been treated.
Discontent reigned on the back benches and proved hugely destabilising.
National's rejuvenation in the second decade of the 2000s is altogether tidier and more dignified. Whether it has the desired effect is a different story.
It is debatable whether many voters pay sufficient attention to know the names or more than a couple of the ministers standing behind the prime minister, and many of those faces - Bill English, Tony Ryall, Maurice Williamson, Murray McCully - have been around since many voters were in shorts.
Will they be fooled by a change of faces on the back bench? Unlikely.
But of course the main value is internal - the injection of fresh blood is a breath of fresh air through a caucus, and encourages fresh talent to join up. It also ensures a Government does not become blind to its weaknesses.
David Cunliffe can only watch and weep.
His backing among the rank and file was as much grounded in a belief that he represented a new generation over Labour's old guard, as it was in the direction he would take the party.
But the likes of Trevor Mallard and Phil Goff have planted their stake in the ground in Hutt South and Mt Roskill respectively.
Their determination to dig their heels in has very little to do with clinging on to the perks of office and everything to do with the fight for the control of Labour which continues to rumble on beneath the surface.
The lack of MPs rushing for the door is as good an indication as any that the hope of seeing off his leadership has not yet died among the caucus rump that bitterly opposed Cunliffe.
That won't change unless the polls put him in an unassailable position.
At that point, expect to see some of Labour's MPs cashing up their super.
- Fairfax Media