"Imagination is in control when you begin making an object. The artwork's potential is never higher than in that magic moment when the first brushstroke is applied, the first chord struck. But as the piece grows, technique and craft take over, and imagination becomes a less useful tool. A piece grows by becoming specific. The moment Herman Melville penned the opening line, "Call me Ishmael", one actual story — Moby Dick — began to separate itself from a multitude of imaginable others. And so on through the following five hundred-odd pages, each successive sentence in some way had to acknowledge and relate to all that preceded. Joan Didion nailed this issue squarely (and with trademark pessimism) when she said, "What's so hard about that first sentence is that you're stuck with it. Everything else is going to flow out of that sentence. And by the time you've laid down the first two sentences, your options are all gone."
It's the same for all media: the first few brushstrokes to the blank canvas satisfy the requirements of many possible paintings, while the last few fit only that painting—they could go nowhere else. The development of an imagined piece into an actual piece is a progression of decreasing possibilities, as each step in execution reduces future options by converting one — and only one—possibility into a reality. Finally, at some point or another, the piece could not be other than it is, and it is done.
That moment of completion is also, inevitably, a moment of loss — the loss of all the other forms the imagined piece might have taken. The irony here is that the piece you make is always one step removed from what you imagined, or what else you can imagine, or what you're right on the edge of being able to imagine. Designer Charles Eames, arguably the quintessential Renaissance Man of the twentieth century, used to complain good-naturedly that he devoted only about one percent of his energy to conceiving a design — and the remaining ninety-nine percent to holding onto it as a project ran its course. Small surprise. After all, your imagination is free to race a hundred works ahead, conceiving pieces you could and perhaps should and maybe one day will execute — but not today, not in the piece at hand. All you can work on today is directly in front of you. Your job is to develop an imagination of the possible."
From Art & Fear