Cyril assumes power - but not over his own party
'Dual use" is the national security theory on the dilemma that arises when something of benefit to humanity can also harm it.
Thomas Friedman, global affairs columnist of the New York Times, this week quoted a security strategist on the US clampdown on China's Huawei: "Everything that makes us powerful and prosperous also makes us vulnerable."
So, Huawei's breakthrough 5G tech infrastructure transfers voice and data at unimaginable speed, but can also serve as an espionage platform for Chinese intelligence.
On the power and vulnerability duality, spare a thought for SA's most powerful and prosperous man, Cyril Ramaphosa.
Yesterday's presidential inauguration caps a long and often circuitous journey. His pinnacles of high achievement were often followed by valleys of apparent defeat.
The union boss who converted the ANC, as its secretary-general, into a vote-winning machine was thwarted as successor to Nelson Mandela.
Denied the deputy presidency, Ramaphosa spurned a cabinet post and concentrated on cementing a new constitution. On its achievement, he quit public life and detoured into business. But he kept his hand in public affairs with his key involvement in drafting the National Development Plan.
Parliament's approval of it in August 2012 - a high point - was followed the next day by the massacre at Marikana, one of his lowest moments.
He was later cleared of any responsibility for the massacre, but it was thought unlikely that he would rebound from that dark stain. Yesterday's celebration at Loftus Versfeld is a reminder of the potency of the comeback.
But, to apply dual use theory: for all the power of his office, and Jacob Zuma's years of misrule are a baleful reminder of its reach, there is a key vulnerability.
Ramaphosa controls the state but he does not have mastery of his party. And the very party and its powerful national executive committee that allowed Zuma to rampage unhindered is now far more attuned to checking a president who wants to do good for his country.
Ramaphosa and the ANC have the virtues of each other's defects and vice versa.
Without Ramaphosa, the party might have lost the election. Yet with him at the helm, the most brazen state-capturers - commencing with (but hardly confined to) Ace Magashule - are at risk.
Equally, without the ANC, Rampahosa would have been a billionaire businessman crafting another deal, not about to announce a new cabinet.
With Magashule now joined at Luthuli House by a David Mabuza unburdened by state duties, watch this duo get to work on not watching Cyril's back, or far worse.
How Ramaphosa squares this circle and keeps his fractious movement together, restores the rule of law to the supremacy the constitution requires of it, and injects life into our listing economy, will be the measure of his success or failure over the next five years. The contradictions are as apparent as the difficulties in resolving them.
Italian polymath Vilfredo Pareto suggested there are two categories of effective leaders - lions who rely on strength and foxes who use cunning. To this taxonomy, The Economist - in reference to exiting British Prime Minister Theresa May - added a third: the tortoise, noting: "Tortoises can do remarkable things in the right circumstances - a thick shell accompanied by plodding purpose."
Tonight's likely disaster for May's party in the Euro elections will reveal the limits of the tortoise approach. There is no victory in "offering something to everyone while convincing no-one", as The Times of London harrumphed.
Her emotional resignation speech on Friday contains a warning to Ramaphosa: it's too late at the end of your term to put right that which you failed to do at the beginning.
A combination of plodding tortoise and strategic fox got Ramaphosa to the summit of power. But the strength of a lion will be needed to convert power into purpose. Let's see.
• Leon is a former leader of the DA and ambassador to Argentina..