Halbwachs' book is a classic of sociology and serves as both a starting point and a reference for memory research, which has become an area of significant importance in history, as well as in cultural and literary studies over the past few decades. In his book, first published in 1925, Halbwachs observes that not only individual people possess memories, but also societies and all forms of social groups develop a collective memory that serves to secure and stabilize their identity. This thesis of a collective memory continues to shape theories in memory research today, as evidenced by Pierre Nora's extensive history of "sites of memory," or "lieux de mémoire.".