As a writer you're holding a dog. You let the dog run about. But you finally can pull him back. Finally, I'm in control. But the great excitement is to see what happens if you let the whole thing go. And the dog or the character really runs about, bites everyone in sight, jumps up trees, falls into lakes, gets wet, and you let that happen. That's the excitement of writing plays-to allow the thing to be free but still hold the final leash.