Michele Da Colle’s account books (1462-63): the first example of double entry in Portugal?

The title of this article puts forward the research question: can the books of the merchant Michele Da Colle be considered as the oldest example of the use of the double entry method in Portugal? Michele was a Tuscan merchant and agent to the Pisan Salviati-Da Colle firm, established in Lisbon as of the second half of the fifteenth century. The first years of his business activity in Portugal are recorded in two account books that are kept today at the Salviati Archive, in the Scuola Normale Superiore of Pisa. To answer the research question, this article thoroughly examines the characteristics of these documents. The aim is to determine if these records follow the general principles of double entry bookkeeping proposed by different scholars. This investigation thus seeks to contribute to the debate on the introduction of double entry in Portugal via Italian influence. The preliminary analysis of these books shows that we are, indeed, in the presence of double entry records. The example does contain formal imperfections, but it has strong similarities with the context of Tuscan accounting of the time, which can arguably mean that it represents a stage of evolution and development of the double entry method. Since we do not have any other examples, Michele Da Colle’s account books can be considered the earliest records in double entry in Portugal. Evidence also suggests that Italian merchants exerted influence on Portuguese merchants for the adoption of this method, although it didn’t last in the centuries to come. This explains why several Portuguese works on arithmetic from the sixteenth century fail to mention the double entry system, which was only regularly applied in Portugal as of the mid-eighteenth century