Tony Abbott has his future in front of him, and may, of course, be prime minister for decades. He may deal well with the economy, and the response of the nation to social, economic and military events abroad, and, perhaps in the future, say something likely to be quoted by his grandchildren. On paper, it looks like he'll get the job, if only from rejection of Gillard, but it is far from clear how he will charm those looking back at him.

He has yet to articulate the idea or the hope that will put him in the history books, least of all for the right reasons. Abolishing the carbon tax won't do it, unless that, as his opponents expect, this later proves some especial act of folly. Nor, by itself, will he rate much for stopping boats, or balancing budgets, even assuming that he does it.

This is not to diminish either the past of Gillard or the future of Abbott. Governing is hard, and the biggest challenges, as Harold Macmillan said, come not from programs and platforms, ideals and ideas, or even people or voters, but from events - particularly those, such as events overseas, over which one has no control at all. Historians may respect and admire calm and steady management of a budget or a program, especially in a crisis, but they also tend to expect and assume it, so that, at the end of the day, it makes little more than a footnote unless one has messed up. What makes the history books or the ''legacy'' is the abiding and enduring idea - that special, and perhaps idiosyncratic, contribution made by an individual over and on top of what one might expect from any common or garden leader.

Experience suggests that leaders cannot necessarily decide what their legacy will be, though some can, looking back, take a degree of credit for things which happened during their term of office. Robert Menzies has two enduring legacies in Canberra and Commonwealth involvement in education and universities. He pushed these hard, though he was in national politics for 20 years before he took much of an interest in either. He deserves more credit than he usually gets for his early war leadership. But it is doubtful, despite his political longevity, that his contributions to economic progress, the law, defence and foreign affairs will get much more than footnote in a a history written 20, or 200, years hence. What does that suggest about short-termers such as Harold Holt, John McEwen, John Gorton and Billy McMahon, except as curiosities by the manner of their departures?

Gough Whitlam will probably get a guernsey beyond the continuing hero worship from baby boomers, but, down the track, much of his legacy may be for contrast, or change of emphasis, rather than vision. (And, like his immediate predecessors, for the manner of his departure.) Malcolm Fraser was in his day a strong man, if these days regarded as irredeemably wet, but, like Bob Hawke, will rate mostly in books dealing with public administration. The personality of Paul Keating - and perhaps his fitful focus on a few issues such as Aboriginal affairs - may earn him a paragraph. As with Whitlam, and to a lesser extent Howard, a few Keating phrases may remain in books of quotations.

John Howard, like Hawke and Keating, warrants reference for opening the Australian economy, and for developing a so far enduring national security state. Kevin Rudd is assured a place only for the apology to the stolen children (and, perhaps, down the track for the cruel hoax of the policies he claimed would repair the damage). Like Gillard, he may well be mentioned, if only over the next decade or so, for a nimble response to world recession. Mere stewardship, under adverse circumstances, rarely rates long.

Some have wanted to be known as ''education'' prime ministers, have tried to attach themselves to technological change, and others have set themselves tasks of abolishing poverty, planting a billion trees, or even, as in the case of Whitlam, to have sewered Sydney, Melbourne and Brisbane. Noble or not, achieved or not, it is hard to imagine year-niners of 2028 (born this year) finding such matters interesting enough to remember.

Barack Obama must step down at the end of this term. No longer having the excuse of having to face voters (if still having to coax change through a hostile legislature), he can now focus on his legacy. What he wants to be remembered for. The lasting changes which will stand as a monument to eight years of his government. The goals and ideals he set for his colleagues, the nation and the world. Evidence that he made a difference, and for the better.

Gillard, facing oblivion, must do so too. No doubt she must temper her aspirations and ambitions with the realities of what her staff and pollsters tell her is popular. She must judge what is realistic and possible given the political situation, the state of the budget, and her limited capacity to influence the world's economy, or even, in the short term, the national economy. Perhaps ''what is right'' matters too.

Such obvious limitations might suggest great caution and little spirit of adventure, lest she frighten the horses. But the polls are against her, and won't change unless she takes risks. And there's the real risk of going out of office, possibly by significant landslide, without anything much in the way of runs on the board. With many of her ''initiatives'' to be undone by an Abbott government. Doomed, down the track, to be remembered only as a curiosity, perhaps a failed experiment.

This does not necessarily mean the dismantlement by Abbott of everything carrying her fingerprints. But successor governments will repackage, rename and put their own DNA all over continuing programs or proposals - such as a national disability scheme. They will get the credit, not her. No one, after the Gillard government, will call it the Gillard National Disability Insurance Scheme, or use Gillard-era titles for her infrastructure, social welfare or indigenous programs.

A quick mental flick through portfolios finds whole areas devoid of results, policies or worthwhile programs capable of enduring or being called a Gillard legacy. Who remembers an ''achievement'' - as opposed to a catastrophe - in agriculture, attorney-generals, defence, finance, immigration, or family services? Is getting on the UN Security Council an achievement? Has anything actually happened with education or health - or broadband or the environment - that anyone can actually put a finger on? To be sure there are words galore, or promises galore, but it is by no means clear that the average citizen sees actual outcomes and results. And even when there are, precious little has been done to market them, and make them political pluses.

Gillard has done what she has said will be her last reshuffle before the election. Two better than average ministers in Nicola Roxon and Chris Evans have gone, but neither can be said to have made much difference likely to endure, except, perhaps with tobacco packaging. Robert McClelland leaves no legacy either. Some remaining ministers actually rate negatively with voters; few have much on offer, either in their own names or Gillard's. It's hard to be more optimistic about the Abbott team; indeed one must wonder what enduring monuments the leader, or the led, have on offer.

Jack Waterford is Editor-at-Large.

jack.waterford@fairfaxmedia.com.au