Each reform, therefore, improving the economical and political situation of the workers proves to be an arm that increases the energy with which the proletarian struggle of classes is fought.

Until 1917 Clara Zetkin was active in the Social Democratic Party of Germany then Clara Zetkin joined the Independent Social Democratic Party of Germany (USPD) and its far-left wing the Spartacist League; this later became the Communist Party of Germany (KPD) which Clara Zetkin represented in the Reichstag during the Weimar Republic from 1920 to 1933. She also adopted the name of her lover the Russian leftist Ossip Zetkin with whom Clara Zetkin had two sons Kostja and Maxim. In 1878 Clara Zetkin joined the Socialist Workers' Party (Sozialistische Arbeiterpartei SAP).

Clara Zetkin (née Eissner; 5 July 1857 – 20 June 1933) was a German Marxist theorist activist and advocate for women's rights. In 1911 Clara Zetkin organized the first International Women's Day.