Lenin wrote this long essay in the first months of 1914, in the last calm before the storm. It appeared that spring in the Bolshevik legal journal Prosveshcheniye in three instalments over the signature "V. Ilyin"; within weeks the July guns would blow apart the International that had promised the workers of every country would never march against one another.

The immediate target was specific. Clause 9 of the Russian Marxists' programme recognised "the right of nations to self-determination", and an array of opponents had opened what Lenin called a crusade against it. Behind them stood the formidable figure of Rosa Luxemburg, whose Polish essay of 1908-09 had argued the slogan was empty, metaphysical, a gift to bourgeois nationalism.

His starting point is a refusal to argue about definitions in the abstract. To ask what self-determination means is not to consult a dictionary of law but to study history, and the history of modern Europe is the history of the nation-state. Read against that background, self-determination "means the political separation of these nations from alien national bodies, and the formation of an independent national state" - nothing vaguer and nothing narrower. It means the right to secede. Not the obligation: Marxists are not in the business of multiplying frontiers, and in most cases will argue for large units and for staying together. But the right must be unconditional, because without it the union of nations can only be a prison, and because only the freedom to go makes the decision to stay worth anything.

The essay's central weapon is still live: its distinction between the chauvinism of the strong and the resistance of the weak remains the sharpest tool available for cutting through great-power hypocrisy, whoever is deploying it.

New critical introduction by Dmitry Chasovennikov.