"The more books we read, the clearer it becomes that the true function of a writer is to produce a masterpiece and that no other task is of any consequence. Obvious though this should be, how few writers will admit it, or having made the admission, will be prepared to lay aside the piece of iridescent mediocrity on which they have embarked! Writers always hope that their next book is going to be their best, for they will not acknowledge that it is their present way of life which prevents them from ever creating anything different or better." (Cyril Connolly, The Unquiet Grave, p. 1)
It is important to keep in mind that The Unquiet Grave is a book of notes made by a man who is not well. "Something is badly wrong," Connolly tells us in his introduction; "he has lost touch with his sub-conscious self, the well is obstructed; he is reminded of a gull fouled with oil" (p. xiv). The plot (such as it is) revolves around "the core of melancholy and guilt that works destruction on us from within" (p. xiii), and it is with this in mind, I think, that we should interpret his opening remark.
Iridescence is the property of surfaces that change their color in shifting light; the rainbow colors on soap bubbles are the classic example. Now, we can dismiss that effect as "superficial" or we can simply appreciate its beauty. It is of course true that many writers are prevented from writing by the way they live, but part of the problem is surely the idea that only a masterpiece is "of any consequence", combined with a "bitter, doubting attitude" (p. xiv). My advice (and, like I say, ultimately Connolly's) is not to abandon your self-styled iridescent mediocrity, i.e., work on that journal article you are writing (or intending to write), but rather to let its iridescence soothe your melancholy and enable you to write. How do you know that it is not the masterpiece you're thinking of?