Frederick Engels was a German political philosopher who, with Karl Marx, developed the communist theory. He was his most efficient helper in the work of organizing the International socialist movement.

“The whole life of Frederick Engels was given up to the emancipation of the laboring class. He stood with Karl Marx by the side of the cradle of the modern labor movement. Their fate was inseparably united with that of the International Social Democracy. Their writings laid the scientific foundation upon which socialism is built. From their works proceeded the clear knowledge which divided the modern social democracy from the dreams of the Utopians. Both were teachers of the laboring class, unfolding to them the actual relation of things. Both were tireless fighters for the rights of the laboring people. They sharpened the sword for us and taught us how to use it. Marx and Engels are the spiritual leaders of the international proletariat, whose inner life they knew better than anyone else. When Engels, hitherto so robust, sank into his grave, his loss was mourned by the laborers of the world and their sorrow knew no bounds of land or speech. Intellectual gifts were lavished upon Frederick Engels. A thorough education embracing every department of human knowledge was accompanied by a rare capacity for theoretic thought.”