When many story-tellers occupy themselves with a social world which offers no great variety of lively action, their stories will probably resemble one another as to many of the major incidents, and if they draw on these limited resources like spend thrifts such resemblances will be inevitable--and therefore not significant.
The artist (I suppose) usually pays for the privilege by some sort of partial insomnia, by the possession of one faculty that will not be controlled nor put to sleep. In a poet this must often be the visual imagination, bringing before his eyes a succession of images which he never summoned, and of which some (it is only too likely) will be ugly or pitiful.
Mannerism, especially when it takes the form of recurrent word or phrase, is by no means easy to represent; there is but a hair's breadth between the point at which the reader delightfully recognizes is as a revealing habit of speech, and the point at which its iteration begin to weary him.