Vladimir Lenin Quote

He who accepts the class struggle cannot fail to accept civil wars, which in every class society are the natural, and under certain conditions inevitable, continuation, development and intensification of the class struggle… To repudiate civil war, or to forget about it, is to fall into extreme opportunism and renounce the socialist revolution.

As quoted in The Military Programme of the Proletarian Revolution, Collected Works, Vol. 23, pages 78-9.