Das Kapital is a treatise on capitalism written by Karl Marx and edited by Friedrich Engels for publication in three volumes throughout the second half of the 19th century. In this famous work, Marx delineates the system by which those who control the means of production are able to exploit the workers who produce the goods, known as commodities, which serve as the engine for capitalism. Marx theorizes in Das Kapital that capitalism relies on the workers to produce the commodities, and yet the workers still suffer from poor wages and working conditions. This exploitation and the constant exchanging of money and commodities, according to Marx, is the backbone of the capitalism.
Marx had already published the Communist Manifesto, his noted work on the struggles between classes, when he turned his attention to capitalism. During that period of history, the Industrial Revolution was taking hold in Europe, and Marx observed the deteriorating conditions that workers faced. This was what inspired Das Kapital, with the first volume being published in 1867 and the second and third volumes, edited by his friend Engels after Marx died, coming out in 1885 and 1894.
It is important to note that Marx did not use Das Kapital as some sort of moral diatribe against capitalists. He described the way that capitalism developed as a sort of historical inevitability. There is also no overt call for workers to revolt in the work. Marx simply felt that the schism that capitalism created between employer and employee was an untenable situation that sowed the seeds for worker unrest.
By exploiting the labor that produces the commodities, Marx felt that the business entities that control the means of production create the conditions that help capitalism to thrive. The workers, who rely on their employers for their wages, are essentially producing wealth for their employers that they are not allowed to share. This system becomes a self-perpetuating machine in which the value of the commodity produced far outweighs the value of the worker who produces it.
Commodities are another central theme of Das Kapital. Marx essentially said that the value of commodities on the market actually bears little relation to their actual usefulness. A commodity's value is defined in terms of what it costs compared to other commodities, which means that the commodities become little more that symbols of wealth to those who purchase them. This never-ending quest for commodities eventually leads, according to Marx, to a contradiction inherent in capitalism, as more and more commodities are produced even as the demand for them dwindles.