ALEXIS Tsipras, likely to be Greece's next prime minister, will have to resolve the latest version of yet another "impossible trinity": relax the economic squeeze, accomplish full-scale debt rescheduling and stay in the euro. Satisfactorily achieving all three aims may be well-nigh unachievable. Mr Tsipras will make a mighty effort, while the rest of the world - drawn to Athens in a way that would never be the case in the absence of crisis - looks on in fascination and bemusement.

After Sunday's sweeping victory by Greece's anti-austerity Syriza, it will be difficult for European leaders, led by Germany, to proclaim "business as usual" in the Sisyphean task of keeping the euro on track to stability. On forthcoming high-profile visits to European capitals, Mr Tsipras will use a mixture of silver-tongued entreaties and old-fashioned financial blackmail to try to get his way.

For the first time, a leader is poised to take power in a member state espousing policies that are diametrically opposite to the euro bloc mainstream. Plenty of other potential pretenders to government office, not least in Spain, where the left-wing Podemos party gave Syriza conspicuous support during the election campaign, wait in the wings.