The publishing of this book was the starting point for an important development in the field of fascist studies. Here, and in his subsequent works, Roger Griffin presented his theory of fascism, which grew and is now one of the dominant approaches (though not without its enemies).
Simply put, Griffin approaches fascism as an ideal-typical construct, using Max Weber's theory of ideal types, arguing that it was, in a now well-know phrasing, a genus of political ideology whose mythic core is a palingenetic form of populist ultra-nationalism. While this may be nigh unintelligible for the average person, once understood, it is a powerful source of clarity amidst the labyrinth of fascism and its theories.
What his theory states, in simple terms, is that fascist ideology is not to be understood by focusing on surface doctrine, but on its core myth, the image that moves its adherents, in this case, the vision of a decadent society and its imminent rebirth in a post-liberal order. Since this is an ideal type, an artificial construct used by political scientists or historians to facilitate analysis and comparison, its real historical permutations could have different concrete roots and ideologies, both left and right, and similarly, fascists could come from both left and right side of the political spectrum. Needless to say, this approach self-evidently includes Nazism as a variation of generic fascism.
Griffin later elaborated this first thesis, for example by incorporating the concept of political religion as proposed by Emilio Gentile, by using Michael Freeden's political morphology and, most recently, by focusing on the aspects of modernity in fascism.
He thus continues the work of such eminent scholars as Eugen Weber, Juan Linz, Stanley Payne, Paul Mazgaj, George L. Mosse or Emilio Gentile, and his theories have become so pervasive that, in 1998, he spoke of an emerging 'new consensus' in the field of fascist studies, one that has the benefit of a considerable heuristic value and usefulness (the most important attribute of a good definition).
For any scholar or student of the phenomenon, this is a must-read, one of the seminal works in the field.