That line applies to creative endeavors, as well.
For me, it applies how I approach writing.
Most of the time, one doesn’t have a very good idea of the story — not on paper anyway. It is clear in their minds, but when it’s translated to the page it is completely different thing.
But, if one has the courage to follow the process, to face the blank page, sudden flashes of inspiration will grow in parts of the story that had not been thought of before. These inspirations come together to bring a completion that could not have been imagined before beginning.
When embarking on a new story, or other creative endeavor, one can do nothing more than believe in the promise.