The free market triumphalism of the 1990s is over. Early 21st century capitalism looks like Karl Marx's description: growing extremes of wealth and poverty, and irrepressible boom-bust cycles. But for the moment, rightwing religious and nationalist nostalgia politics is the main beneficiary of the opposition this has spawned. The political left remains in the shadow of its disastrous failures in the 20th century. The centre-left - where it has not joined forces with the neoliberal right - clings to nationalist and bureaucratic-statist nostalgia for the social-democratic Cold War era. The far left clings to the coat-tails of the centre-left. It cannot unite itself - let alone anyone else - because it is unwilling to reinterrogate the ideas of the early Communist International, especially on the 'revolutionary party'. To move beyond this impasse we need to re-examine critically the strategic ideas of socialists since Marx and Engels' time. This book begins the task.