Final answer:
Karl Marx and Friedrich Engels published the Communist Manifesto, which introduced their concept of class struggle and predicted the transition from capitalism to socialism and communism. Marx's ideas were further developed in Das Kapital, critiquing capitalist society and labor exploitation.
Step-by-step explanation:
Karl Marx and Friedrich Engels published their revolutionary ideas in the Communist Manifesto in February 1848, coinciding with a period of widespread revolutionary activity in Europe. Marx's theories on class struggle and capitalism were further expanded in his seminal work, Das Kapital, the first volume of which he published in 1867. The second and third volumes were edited and published posthumously by Engels. These publications laid the foundation for Marxism and predicted the eventual transition from capitalism to socialism, and eventually to a classless society known as communism.
The Communist Manifesto is renowned for its analysis of history as a series of class struggles and its call for the proletariat to rise up against the ruling classes. Marx's profound critique of capitalist society in Das Kapital highlights the exploitative nature of labor and production under capitalism. Despite Marx never witnessing a socialist revolution during his lifetime, his ideas had a significant impact, influencing socialist parties and eventually contributing to the establishment of communist states in the 20th century.