How we cite our quotes: (Chapter.Section.Paragraph) or (Chapter.Paragraph)
Quote #1
My view is that each particular mode of production, and the relations of production corresponding to it at each given moment, in short 'the economic structure of society', is 'the real foundation, on which arises a legal and political superstructure and to which correspond definite forms of social consciousness', and that 'the mode of production of material life conditions the general process of social, political and intellectual life'. (1.4.17)
According to Marx, tradition and customs derive from economic life. For example, the custom of going out on Thursday night—because entertainment venues are open late then—derives from the weekend arriving on Friday. And that derives from Henry Ford in 1926 initiating the five-day workweek in order to increase productivity by having better-rested workers.
Quote #2
One thing, however, is clear: nature does not produce on the one hand owners of money or commodities, and on the other hand men possessing nothing but their own labour-power. This relation has no basis in natural history, nor does it have a social basis common to all periods of human history. It is clearly the result of a past historical development, the product of many economic revolutions, of the extinction of a whole series of older formations of social production. (6.7)
Marx says the existence of a capitalist class that hires workers depends on the extinction of past ways society has organized production. The tradition and customs arising from those past modes of production are largely forgotten now, so much so that Marx felt he had to make a point of saying that capitalism is just a historical phase, not a permanent condition of existence.
Quote #3
The appearance of products as commodities requires a level of development of the division of labour within society such that the separation of use-value from exchange-value, a separation which first begins with barter, has already been completed. But such a degree of development is common to many economic formations of society, with the most diverse historical characteristics [...] The historical conditions of [capital's] existence are by no means given with the mere circulation of money and commodities. It arises only when the owner of the means of production and subsistence finds the free worker available, on the market, as the seller of his own labour-power. And this one historical pre-condition comprises a world's history. Capital, therefore, announces from the outset a new epoch in the process of social production. (6.8-9)
Many modes of production, not just capitalism, have commodities and money. What sets capitalism apart is the existence of a proletariat, that is, people who can sell their labor-power to employers. That one change caused unique traditions and customs to spring up over time.