On the day before President Jacob Zuma fired Finance Minister Nhlanhla Nene, the Financial Mail carried a prescient image on its cover. It showed Nene and the Reserve Bank governor, Lesetja Kganyago, in a boat with Zuma. Both were rowing furiously to prevent the boat from going over a waterfall while Zuma sat back, barely concerned. The caption on the cover was "On the verge of fiscal suicide".The next day, fiscal suicide was committed when Zuma axed Nene and replaced him with back-bencher David "Des" van Rooyen.The financial markets rewarded the decision by selling the rand to below R15 to the dollar and the bond market reacted with panic.Zuma's timing was cynical - he made the announcement just days after major rating agencies downgraded their view of South Africa's financial prospects to a hair's-breadth above junk status. If the announcement had occurred before the downgrade the agencies would have gone all the way.What was shocking about Zuma's decision was its implications for an institution which has been vital to the story of post-apartheid South Africa - the Treasury.Say what you will about the failure to deliver education, health and other services, about continued rampant crime and the other failings of the government, but you would always have to halt your criticism at the door of the Treasury.A succession of finance ministers have held the line on government spending and retained the faith of the world in South Africa's fiscal regime.The towering figure of Trevor Manuel, the first ANC finance minister, comes to mind. He had the clout to call the shots on expenditure in the Mbeki years and, to the president's credit, he was allowed to do so.The Mbeki-Manuel partnership produced the only period in post-apartheid history in which the economy grew at above 5% - for three years in a row. They even produced a now unthinkable budget surplus.When Mbeki went, Zuma humoured Manuel for a while before shifting him out of finance to draw up the National Development Plan.Manuel was replaced by Pravin Gordhan in May 2009. After a five-year term, Gordhan was replaced by Nene in May last year.Whereas Mbeki prized the solid continuity offered by the incumbency of Manuel, Zuma appeared to have a different agenda.When Manuel's National Development Plan emerged from years of incubation, it continued the tradition established by years of fiscal prudence. The government was to sort out its relationship with the unions (education), bring discipline to bear on its officials (no moonlighting in business) and stimulate the economy by encouraging the private sector to invest.The National Development Plan sat uncomfortably next to a very different economic agenda called the New Growth Path, developed by Ibrahim Patel, for whom the new post of minister of economic development had been created. Why the new portfolio, many wondered. Wasn't the finance minister by definition already the minister of economic development?Patel's plan placed the government at the centre of the economy, regulating, controlling and forcing the private sector into developing the public sector.Pressure began to mount on Gordhan and then on Nene to loosen up the Treasury.Nene responded by holding the line, making little mention of the unrealistic plan to spend north of R1-trillion on nuclear plants in his speeches and calling for an end to the lavish spending habits of some ministers. And, when Zuma's friend, the untouchable head of SAA, Dudu Myeni, wanted to renegotiate an agreement to scrap the purchase of planes, a move that would cost hundreds of millions of rands, Nene said "No".It took balls. Exactly a week ago, Nene issued a public statement in which he made it plain that Myeni's plan was expensive and wrong. The sting came in the last sentence, which read: "Should SAA conclude a significant transaction with Airbus or any other party for which the airline has not received approval in terms of Section 54, this would constitute an act of financial misconduct which could be grounds for sanctions against the board in line with Section 83(4) of the PFMA."He was telling Myeni in no uncertain terms that he would fire her if she went ahead with this plan. He was sealing his fate.And so Zuma made the call that has shocked the nation. Instead of reining-in Myeni and asking the Treasury to cost properly and advise on the nuclear building plan, he fired Nene.In his place he appointed the barely known Van Rooyen, a man who has publicly called for the country to run a larger deficit and who has expressed his admiration for Patel's New Growth Path.Van Rooyen will face the same pressure as Nene and he had better give in or he will suffer the same fate. Zuma has unlocked the door to the Treasury. Inside he will find the glittering promise of gold.He's got three years to spend it...