Professionalization is the social process by which any trade or occupation establishes the group norms of conduct, acceptable for membership of the profession, a professional body or association to oversee the conduct of members of the profession, and some degree of demarcation of the qualified from unqualified amateurs. The transformation into a profession brings about many subtle changes to a field of inquiry, but one more readily identifiable component of professionalization is the increasing irrelevance of "the book" to the field: "research communiqués will begin to change in ways [...] whose modern end products are obvious to all and oppressive to many. No longer will member's researches usually be embodied in books addressed [...] to anyone who might be interested in the subject matter of the field. Instead they will usually appear as brief articles addressed only to professional colleagues, the men whose knowledge of a shared paradigm can be assumed and who prove to be the only one able to read the papers addressed to them." Philosophy underwent this process toward the end of the 19th century, and it is one of the key distinguishing features of the contemporary philosophy era in Western philosophy.