. . . by lack of finish. A commonplace idea when well told is more acceptable than a brilliant thought poorly expressed.
Always go over your stories. Close and rigorous scrutiny will often reveal some flaw, and a flaw, no matter how small, spoils the story. Errors of grammar, spelling, and punctuation must be corrected, for, though the tale is good, an editor has no time to correct such mistakes. Thorough revision of structure, style, and punctuation will save you many postage stamps.
It is desirable that you should have some talent to begin with, but talent without perseverance is of little use. Success in literature, as in other things, is largely a matter of hard work.
Editor's Note:
It is to be hoped that the rest of this exists somewhere. It would be quite something to know whether this was part of a general essay on "The Writer’s Art," or part of a letter of advice to some fledgling author; it may also be general thoughts on the subject for his own reflection.