Esquerdismo by Vladimir Il’ich Lenin

An Infantile Disorder

A forceful critique of ultra-left sectarianism arguing that refusing to use parliaments, trade unions, and legal forms of struggle isolates revolutionaries from the working class and weakens the movement; drawing on recent revolutionary experience, it defends disciplined party organization, tactical flexibility, and mass work (including participation in imperfect institutions) as necessary to build broad support, while warning that dogmatic purity, spontaneity, and adventurism will prevent the successful preparation for and seizure of state power.