The days when you don't write after trying to for hours - these days matter.
I tell myself this at the end of such a day.
I call them waiting days or gathering days or gestating days.
Days when all that happens is the clouds gather and build and take form and shape and color.
Except you can't see them.
You're not the sky on such a day.
You're just a person in a chair, out of a chair, walking, sitting, eating, walking, sitting, reading something old you wrote and marveling that the words found their way to a page.
So-you are not the sky and you cannot see the clouds but you feel they are forming and you know from other occasions in your writing life - because you are a writer, remember - you know such days come to pass, such clouds come to form.
And then it rains.