In this period, Europe underwent a ruinous economic and social depression which arrested the development of urban progress and imposed new forms of organization in social life. This process is exceedingly tortuous: it varies from nation to nation and presents complications and contradictions which are particular to Italy. Numerous famines interrupted the rhythm of agricultural production and the general state of resultant malnutrition and physical weakness facilitated the diffusion of illnesses and epidemics. The first wave of the Black Plague, carried to Europe from the East by rats stowed away on merchant ships, lasted from 1348 to 1351. Successive waves of the plague took the lives of roughly one third of the population in Southern Europe.
From the middle of the century onward, this significant reduction in the number of laborers and professionals occasioned a severe collapse in the financial structure of the region. In fact, the state of general economic insecurity was accentuated by wars which added their destructive effects to those brought on by famine and plague. The recession struck Italy just when the urban and mercantile civilization had reached its highest point of development and the merchants of the principal cities of the peninsula had acquired control of the most important international markets.
The result of this series of catastrophes was, however, less a complete collapse than it was the onset of a period of relative stagnation which provided the merchants with a more energetic consciousness of their capability to survive in the face of grave misfortune. They began to consider themselves more and more as a fundamental part of the social fabric, maintaining at once privileged relationships with the aristocracy and the city nobility.
From the local wars and epidemics that continued one on the heels of another throughout the century, a new system of government was born. The formation of this original institution advanced in equal measure with the progressive decline in the city-state system in Northern and Central Italy and with the diffusion of Signorie, regional governing bodies. This process had already taken shape in the previous century but was accelerated by the economic depression which rendered the city-state structure increasingly more fragile. These new governments grew up around wealthy, landed individuals and soon expanded to include the neighboring countryside.
(G.M. M.P. S.P.) Muscetta, Carlo. "Giovanni Boccaccio." Letteratura italiana Laterza, (Bari: Laterza, 1989). Ferroni, Giulio. Storia della letteratura italiana, vol. I "Dalle origini al Quattrocento" (Turin: Einaudi, 1991).