This contribution investigates the role played by credit during business cycles as well as financial and economic crises. More specifically, we will focus on credit demand behavior but also on the evolving institutional rules which favour and limit this demand as far as the organization of the financial and banking system is concerned. The theory and the history of business cycles can both be very useful from this standpoint. Credit excesses and the importance of the leverage effect are not new phenomena but they exerted their influences in a majority of business cycles which took place in different parts of the xixth century. These historical and analytical investigations do provide adequate tools for an analysis of the formation of a collective belief according to which the permanent reinforcement of the limitation of corporate liability and of the risk transfer is the condition of an efficient system of financing and funding.
From this standpoint, after having recalled the importance attributed by Clément Juglar to credit in the explanation of business cycles, the contribution focuses on the financial and economic crises of 1866, 1882, 1929 and 2007, and draws some general conclusions allowing a better understanding of the weight of credit excesses in the origin of crises.