Coming from the upper industrial bourgeoisie of Wuppertal, the young Friedrich Engels much preferred philosophy and politics to business. Having observed in the family textile factories, especially in Manchester, the appalling living conditions of the workers, he theorizes the relations between bourgeoisie and proletariat by relying on the Hegelian dialectic, studied in Berlin. The meeting in 1844 with Karl Marx, whose ideas he shared, sealed an indelible friendship, punctuated by travels, and an intellectual collaboration among the most fruitful in history. From the "Manifesto of the Communist Party" to "Capital", of which Engels will rework and publish the last volumes after the death of his friend, their two names will remain inseparable.