It’s interesting to listen to the chorus of voices telling Malcolm Turnbull not to go for the Liberal leadership so soon: first-term opposition leaders are doomed, it could ruin his career, better to let someone else take the first turn. Peter Brent this morning says that a Labor landslide in 2010 “would squash his political prime ministerial aspirations, probably forever.”

There are a few answers to that. One is that the prospects for first-term opposition leaders are not all bad. True, none has won federally since Andrew Fisher in 1914, but the last two – Andrew Peacock and Kim Beazley – both came very close: Beazley won a majority of the vote at his first attempt, and Peacock did the same at his second.

Another answer is that one cause of the Liberal Party’s predicament is its leaders’ habit of only looking out for themselves, and never considering the future of the party as a going concern.

More than anything, the party needs a philosophical reorientation, and Turnbull is the only leadership contender who has anything like the credentials to provide it. Even if he never leads it to victory, he would earn his place in history if he successfully took on the task of bringing Menzies’ party into the twenty-first century.

But the most compelling answer is that opportunity rarely knocks twice.

You have to seize the moment when it presents itself; the candidate who says “not just now, I’m not ready yet”, is unlikely to be given a second chance.

Turnbull should know that, because he has in front of him the example of the last person to say that – and incidentally, the last person to be marked out as the great white hope of the Liberal Party’s left: Peter Costello, who failed in his ultimate ambition because he turned opportunity down, not once but three times.

Costello could have had the leadership in 1994, but he judged (reasonably, but wrongly) that the next election was a write-off and therefore the time was not ripe. So instead the party got Alexander Downer and then John Howard, who comprehensively remolded it in their own flawed image.

Twice more Costello could have grasped for the top job: in 2003, when Howard ratted on his “when I’m 64” commitment, and again less than three months ago, when the party was ready to desert Howard but Costello, understandably enough, was reluctant to take charge of a sinking ship.

So far, Turnbull is showing the nerve that Costello lacked. If he takes the leadership now, let’s hope he proves equal to it, and that fortune rewards his courage.