assume a priori that in every case we have secondary, pseudepigraphical attribution of authorship.’31 Hengel argues that titles were a practical necessity when there was a concern to distinguish between different works and authors, for example in selling books, in academic discussion and in libraries, particularly in the Hellenistic period. By the Christian era most books had already been given a title by their authors or by pupils, friends or patrons, exception arising if a book was not to be public.