The introduction sets the theme of the book by illustrating an experience of intense, rapid change which can lead to a loss of self, arguably a key modern experience and not one unique to the twenty-first century. I argue that there was an intense sense of profound societal transformation at the end of the nineteenth century, when the discipline of sociology was born. Most crucial, it is analytically fruitful to reinvigorate classical crowd theory in order to understand individuality and collectivity, both then and now. I situate this main argument vis-à-vis existing discussions of modernity as well as present an outline of the book’s chapters, along with a brief discussion of the montage approach deployed in the book.