How the concrete-abstract emerges in history differently from in thought: "But this is by no means the process by which the concrete itself comes into being. For example, the simplest economic category, say e.g. exchange value, presupposes population, moreover a population producing in specific relations; as well as a certain kind of family, or commune, or state, etc...The totality as it appears in the head, as a totality of thoughts, is a product of a thinking head, which appropriates the world in the only way it can, a way different from the artistic, religious, practical and mental appropriation of this world. The real subject retains its autonomous existence outside the head just as before; namely as long as the head’s conduct is merely speculative, merely theoretical. Hence, in the theoretical method, too, the subject, society, must always be kept in mind as the presupposition...the most general abstractions arise only in the midst of the richest possible concrete development, where one thing appears as common to many, to all. Then it ceases to be thinkable in a particular form alone. On the other side, this abstraction of labor as such is not merely the mental product of a concrete totality of labors. Indifference towards specific labors corresponds to a form of society in which individuals can with ease transfer from one labor to another, and where the specific kind is a matter of chance for them, hence of indifference." (Marx. Grundrisse.)
