 Some sources suggest that Giovanni di Bicci de' Medici introduced this method for the Medici bank in the 14th century.The double entry system began to form for practice in Italian merchant cities during the 14th century, before then there could be systems of accounting records on multiple books which, however, do not yet have the formal and methodical rigor necessary to control the business economy.In the course of the 16th century, in Venice is born theoretical accounting science by the writings of Luca Pacioli, Domenico Manzoni, Bartolomeo Fontana, the accountant Alvise Casanova and the erudite Giovanni Antonio Tagliente.