The Syriza victory in the May European elections was historic – it is the first time the radical left has won in Greece – and the celebrations of party supporters outside Athens University lasted until the early hours. The emotional but restrained mood captured the melancholia of a nation torn between an invented tradition of classical glory and a traumatic history of state repression, corruption and dynastic politics that brought the country to the edge of disaster. The elections marked the end of the post-civil war period. Shared hardship makes the old left-right divisions recede.

On a stage three young people sang and danced: Alexis Tsipras, the leader of Syriza; Rena Dourou, the winner of the Attica region, where close to half the population of Greece lives; and Gabriel Sakellaridis, who lost by the smallest margin the Athens town hall. At the edge of the crowd an older couple were crying. "We have been waiting for this day for 70 years," the woman said.

These people capture the two sides of the Greek left. On one, the civil war refugees – leftists exiled in barren islands and hostile mountainsides, the imprisoned and executed – who finally found themselves on the winning side. Manolis Glezos, the 92-year-old man who lowered the swastika from the Acropolis in June 1941 and spent a large part of his life in prison, received close to half a million votes, by far the largest number. On the other side, stands the 60% of young people aged 18-24 who are unemployed, along with the squeezed middle-aged and middle-class people, all of whose lives have been devastated by austerity and who stood up and resisted.

The deprivations and degradations suffered daily by ordinary Greeks over the past few years have been well documented in this paper. The persistent public as well as low-profile resistances have been discussed less. Europe used Greece as a guinea pig to test how late capitalism in crisis can be restructured with substantive reductions in wages, pensions, health, education and social services. What took the European and Greek elites by surprise was the determination of the guinea pig to transform itself from object to political subject.

This transformation was not unexpected. There comes a time when an economic and political system becomes obsolete and harmful. Yet two more elements are necessary before it departs the stage: a political subject prepared to take power; and a catalyst, a spark, that will kick off the disintegration of the regime. All three converged in Greece: the near universal popular rejection of the corrupt and disastrous political, economic and media elites; Syriza as the agent of change; and, finally, the troika and its austerity diktat as the symbol of all that has gone wrong.

The journey of Syriza from a small protest party to government-in-waiting is a political fairytale. The party polled 4% in 2009, became the main opposition in 2012, and received 27% of the vote in the European elections, with the rightwing governing party down to 23%. The transformation started in the occupations of the squares in 2011: the Greek resistance was understandably sidelined by the Arab spring and the Occupy movement but it was clear that the Greek spring had the greatest chance of success.

Syriza, a highly democratic coalition of small euro-communist, ecologist and socialist parties (since unified into a single organisation), participated fully in the occupations without the usual leftist drive to dominate. When the multitude of the squares looked for parliamentary representation, it adopted Syriza as the party of change and raised it from relative obscurity to the future government.

Is Syriza ready to govern? Between the breakthrough 2012 and the 2014 elections the party has developed a set of policies to kick off economic growth and political renewal. A governing Syriza will raise the minimum wage, reintroduce collective bargaining, and repeal the measures that have led to economic collapse and a humanitarian crisis. It will ask for a substantive haircut of the debt to make it viable – at the start of the crisis the debt was 120% of GDP, after four years of austerity it stands at 175% – and will peg repayment of the rest on economic growth.

Furthermore, the party will defend national sovereignty against the neocolonial policies of the troika, which have suspended the minimum guarantees of the rule of law and the social state. National identity can be radical and patriotic, or exclusionary and xenophobic. To stop the rise of extreme rightwing ideologies, which are an acute problem in Greece, the left must redefine the meaning of patriotism and rescue it from racists.

Finally, Syriza promises a defence of democracy. Neoliberal capitalism has replaced democratic governments with technocratic governance that has turned citizens away from politics. Only a different conception that combines direct and representative democracy can gather popular support. Participatory democracy, the legacy of the occupations, must be breathed into the mainstream political system. By promoting social justice and democracy, the left becomes the heir to the Enlightenment principles of freedom, equality and solidarity.

Can the Greek left succeed? Its clean past and commitment to universal values creates a major moral advantage, but more is needed. The left must combine principle and pragmatism, radical politics and social mobilisation. It is a tall order for a small country and organisation. But it is the only hope for Greece and Europe against the rising Euroscepticism of the right. If it succeeds, the Greece of resistance will become the future of Europe.