When you start searching for ‘pure elements’ in literature you will find that literature has been created by the following classes of persons:  Inventors. Men who found a new process, or whose extant work gives us the first known example of a process. 
   The masters. Men who combined a number of such processes, and who used them as well as or better than the inventors. 
   The diluters. Men who came after the first two kinds of writer, and couldn’t do the job quite as well. 
   Good writers without salient qualities. Men who are fortunate enough to be born when the literature of a given country is in good working order, or when some particular branch of writing is ‘healthy’. For example, men who wrote sonnets in Dante’s time, men who wrote short lyrics in Shakespeare’s time or for several decades thereafter, or who wrote French novels and stories after Flaubert had shown them how. 
   Writers of belles-lettres. That is, men who didn’t really invent anything, but who specialized in some particular part of writing, who couldn’t be considered as ‘great men’ or as authors who were trying to give a complete presentation of life, or of their epoch. 
   The starters of crazes.Until the reader knows the first two categories he will never be able ‘to see the wood for the trees’. He may know what he ‘likes’. He may be a ‘compleat book-lover’, with a large library of beautifully printed books, bound in the most luxurious bindings, but he will never be able to sort out what he knows to estimate the value of one book in relation to others, and he will be more confused and even less able to make up his mind about a book where a new author is ‘breaking with convention’ than to form an opinion about a book eighty or a hundred years old.He will never understand why a specialist is annoyed with him for trotting out a second- or third-hand opinion about the merits of his favourite bad writer. 
 
Ezra Pound, ABC of Reading
writers, writers-on-writing