Writing a first draft is like groping one's way into a dark room, or overhearing a faint conversation, or telling a joke whose punchline you've forgotten. As someone said, one writes mainly to rewrite, for rewriting and revising are how one's mind comes to inhabit the material fully.
When I'm wrong I'm like the Emperor on the Death Star thinking he'll turn Luke. Yet, when I'm right I'm a Jedi like my father before me.