The observations of Marx and Engels led to their work, which is a critique of capitalism.
Karl Marx is the most erudite socialist thinker to emerge in the 19th century. Although he was greatly involved with social, economic and political ideology gained rapid recognition in the socialist movement after his death in 1883. While in Brussels Marx devoted him to an extensive research on the history and elaborated what came to be known as the materialist conception of history He developed in a manuscript (published posthumously as the German Ideology), of which the basic thesis was that the nature of individuals depends on the material conditions determining their production. Marx pointed out the history of the various modes of production and predicted the abolition of industrial capitalism and its replacement by communism. He devoted himself to the study of political economy in order to determine the causes and conditions of this crisis.
Marx discovered the law of development of human history. The simple fact is that mankind must first of all eat, drink, have shelter and clothing, before it can pursue politics, science, art, religion, etc. Therefore, the production of the immediate material means, and consequently, the degree of economic development attained by a given people or during a given epoch. By laying the foundation upon which the state institutions, the legal conceptions, art, and even the ideas on religion, of the people concerned, have been evolved.
Karl Marx discovered the special law of motion administering the present-day capitalist mode of production, and the bourgeois society that this mode of production has created. The unearthing of surplus value abruptly threw light on the problem, in trying to solve which all previous investigations, of both bourgeois economists and socialist critics, had been groping in the dark.
Marx authentic mission in life was to contribute to the overthrow of capitalist society and of the state institutions, which it had brought into being, to contribute to the liberation of the modern proletariat.