Paul Hazard, deep connoisseur of the neolatin literature, well-deserving of the diffusion of Italian literature and art, is known especially for his famous work The crisis of European consciousness, 1680-1715. Not many people know about this study about Leopardi (1913), published when he was a lecturer in the Faculty of Arts courses in Lyon. Of course, the bibliography of Leopardi has increased dramatically in the last century : we know everything about women and love affairs, sources and tormenting joints of his thought. But this work is useful to reconstruct an historical context, and to return with the memory to the recovery of a very knowledgeable work, that in the early twentieth century, was definitely at the forefront in France.