Northern Italy is characterised by a widespread interpenetration of agricultural and manufacturing labour long before the industrial revolution. However, the concept of proto-industry has been developed by Mendels for continental Europe by considering the weaving of hemp, wool and linen. The Dutch-born historian argues that the seasonal alternation between manufacturing and agricultural labour caused an unlimited supply of labour during the winter period, which kept wages low and makes rural industry competitive. This pattern has nothing to do with the silk industry, since sericulture is characterised by an extremely short cycle with a high labour intensity taking place at the beginning of summer, when the fields require the most labour. For Northern Italy, the question of proto-industry must therefore be approached in the opposite way to continental Europe: why introduce fibre labour that takes labour away from the traditional rural enterprise? This chapter argues that silk constituted the very material basis that allowed the capitalistic organisation of Lombardy’s economy between the eighteenth and nineteenth centuries. In particular, the author explores the double role of cocoons as commodity money capable of providing the basis for an initial capital accumulation for North Italy that would become one of the sources of the territorial divide still standing in the Italian economy today.