Over the years, Marc Fumaroli has studied and frequented assiduously "that ideal society, and yet nonetheless real, that up to the French Revolution went beyond the political and religious geography of Europe constantly having the Ancient as heritage and object of studies", and that "it is itself called for four centuries and in all the languages ​​Republic of Letters". This book collects the essence of what he has written on the subject, which thanks to him has returned to being unavoidable in any study on European culture. Born with the great passion of Petrarch to bring back to life the buried treasure of ancient humanitas and its urbanitas by force of excavations, and developed in the Florence of Marsilio Ficino, "that society of friends and equals" has passed through the centuries, transferring its capital from Florence to Rome, from Rome to Venice, and from here to Aix and Paris, which will compete with London and Amsterdam. On the basis of what Fumaroli calls "the sublime treatise Del Sublime" - and which indicates only one way to "escape modern sterility", in order to "isolate oneself from one's time of decadence": turning to the great epochs, returning to those masterpieces of the past "who have something divine" - the members of the Republic of Letters ("great souls, born too late") have long constituted, thanks above all to the exchange of letters, what may have been the only successful supranational entity, "a great invisible and firm city".