You've heard the myth. of course, the one about the artist afraid of the blank canvas... All poppycock! To him it's not an empty space. It holds, if not the first trace of his image, then at least the terms in which to spell it out. It is not total freedom, a blank page on which to write whatever comes (which would be scary), but constraint. Around the canvas edge (where later on, the frame will go) he thinks a fence or hedge to isolate his marks, to keep them safe from all that might contaminate - for this is what he fears, the failure of his inner sight. l'art pour l'art - in other words: KEEP OUT! TRESPASSERS WILL BE PROSECUTED! Let's say his image is a beggar man, a line of refugees... He feels a pity... this is what he must keep out. Here failure lurks, for this is what he fears - the image, having been adulterated, will be too weak to stand alone, will need to borrow feelings, sentiments, emotions from somewhere alien beyond the frame. The pity that we want will emanate from shapes and colours that belong to what goes on within the working space. Mostly though, we do not act like that: the fence is porous, signs ambiguous, grown over, out of date; we read things into what is there, forget each piece of art is an event, a new piece of reality and not a copy of a bit grown old. So art becomes a starting point, we're not content to stay within the frame. With poetry it's just the same. The truth is words are never good enough, but having nothing else, we must protect their probity. Musicians know the score! They do not add strange meanings to pure sound. Their less is greater than our more.
(I do so hope you've realised that this poem advocates all that it isn't!It was written for the excellent prompt at poetry jam.)