The methodological problem of the shift from a history of art based on the analysis of the works to a new understanding of the link between iconological study and the reconstruction of the economical value of commission, is exemplified with the situation in Milan in the second half of the seventeenth century. Here the faction guided by Bartolomeo III Arese (1610-1674) develops in its great palaces (especially that in Cesano Maderno) a complex system of different values. Galileism, panpsychism, cabalism and quietism were expressed through the choice of a classicism with strong Roman traits, represented by archaeological Quadraturismo and panistic representations of nature. From the economical point of view we reconstruct the incidence of the great art commissions on the annual finances of the Arese and Omodei households, thus observing a total expenditure which was distributed through time (from five to thirty years according to the different buildings) and with a regular incidence of 10-15% of the income. This new element allows a different evaluation of the strategies of art commission and of the dialectic between Milanese residences, the great residential palaces outside Milan and the feudal residences which were usually well distinct.