Karl Marx argued that alienation is a direct consequence of the capitalist mode of production, where workers are separated from the products of their labor and their own human potential. He proposed that the transition to communism, characterized by the collective ownership of the means of production, would eliminate class distinctions and restore the connection between workers and their labor.

Karl Marx published 'A Contribution to the Critique of Political Economy' in 1859. This work is significant for containing his famous preface, which outlines the materialist conception of history. In this text, Marx explains how the economic base of society (the mode of production) determines the superstructure, which includes legal, political, and cultural institutions, thereby shaping the overall social consciousness.

Marx distinguished between a 'class in itself' (a group sharing a common economic position) and a 'class for itself' (a group with class consciousness and political organization). He argued that the development of factory production and the labor movement would foster solidarity among workers. This process would lead them to recognize their shared interests and organize collectively to challenge the ruling class, thereby transitioning from a passive group into an active, revolutionary 'class for itself'.

The 'mode of production' is a central concept in Marxism, referring to the specific way a society organizes its economic activity. It encompasses both the 'forces of production' (tools, technology, raw materials, and human labor) and the 'relations of production' (the social relationships, such as class structures, that govern how production is organized and how the output is distributed).

Friedrich Engels was a close collaborator of Karl Marx. Together, they co-authored seminal works such as 'The Communist Manifesto'. Engels provided significant financial and intellectual support to Marx, and his own writings, such as 'The Condition of the Working Class in England', were instrumental in shaping the foundational principles of socialist and Marxist theory.

Marx argued that surplus value is created when workers produce more value than they are paid in wages. In a capitalist system, this surplus is appropriated by the owners of the means of production, manifesting as profit, which is the primary driver of capital accumulation.

Karl Marx argued that the mode of production—the combination of the forces of production and the relations of production—forms the economic base of society. This base fundamentally shapes and determines the superstructure, which includes the social, political, and intellectual relations of that society.

The materialist conception of history, primarily associated with Karl Marx, emphasizes economic structures, modes of production, and class conflict as the drivers of historical change. 'The spirit of capitalism' is a concept famously associated with Max Weber's work, which explores the cultural and religious influences on economic systems, rather than the materialist framework developed by Marx.

Marx famously described religion as the 'opium of the people.' He argued that religion functions as a form of alienation, where individuals project their human essence onto a divine entity. This process distracts the proletariat from their real, earthly struggles under capitalism, creating a false sense of hope and community that serves to maintain the status quo and perpetuate social inequality.

Marx employed the dialectical method, rooted in Hegelian philosophy but applied to material conditions. This approach posits that social change is driven by the internal contradictions within a society's economic base, specifically the conflict between the forces of production and the relations of production, leading to historical evolution.