It’s four hundred years since Shakespeare’s Macbeth warned us in unforgettable imagery of how unbridled ambition could destroy a person’s moral compass and ultimately their life. Unfortunately, some politicians still haven’t learned the lesson.

An obvious case involves Tony Blair and Gordon Brown, now locked in a dance of death over the leadership of the British Labour Party. But an even clearer example can be found closer to home in the fall of Victorian Liberal leader Robert Doyle.

Four years ago, Doyle was in the box seat. The Victorian Liberals, led by Dennis Napthine, were facing certain defeat in the 2002 state election. Doyle was the heir presumptive; the only possible candidate who represented a clear break with both Napthine and previous leader Jeff Kennett. Had he simply bided his time, he would have taken over a party not exactly united – in Victoria that is too much to hope for – but strongly supportive of his leadership. He would have had a full four years to rebuild it to take on the Bracks government.

But Doyle couldn’t wait. Ambition drove him to believe, against all the evidence, that he could make an immediate difference: that with him as leader, the election would be something other than a wipeout. He continued to destabilise Napthine’s leadership, and when Napthine demanded a pledge of loyalty from him he refused, and launched a challenge instead, which he won.

Under Doyle, the Liberals suffered the worst defeat in their history. Since then, he has been a dead leader walking – politicians just don’t come back from results like that – until his final admission last week that his position was untenable. Now another leader, Ted Baillieu, has been put in the same unenviable position.

It could all have been so different, if ambition had not blinded Doyle to reality four years ago. Instead, his personal and political life has been shattered, and he will be remembered as his party’s least successful leader. The best he can hope for is the quiet oblivion that Macbeth was denied.