ABSTRACT
"Psychology is in need of its own Das Kapital", wrote Vygotsky in 1928, observing that "the whole of Das Kapital is written according to this method",, the method in which Marx identifies the cell of bourgeois society-an exchange of commodities-and then unfolds from an analysis of the contradictions within this single cell, the entire process of bourgeois society. The term Marx used for the concept of 'cell-form' is referred to in cultural-historical activity theory by two different terms: 'unit of analysis', and 'germ cell'. These are two different expressions for the same concept, but they indicate two different aspects of the same concept. Germ cell indicates the germ from which more complex forms develop, just as the embryo grows into the mature organism. A unit of analysis is always used for the analysis of some specific problem. Rather than psychology on one side and social theory on the other, Vygotsky has given us the opportunity for a genuinely interdisciplinary science.
