Taken from an interview with Jane Hirshfield:
For me, words were not about pleasing or entertaining others but about creating a place of refuge, where I could find something out about what it means to have and be a self. Scholars say that introspection only became truly possible with the development of writing. Writing allows the self to be set down and looked into, questioned, changed. On those unseen late night pages, I could experiment, I could fail, it didn't matter. There is an immense freedom to writing for oneself alone. This is something I still feel. I wrote most often in the middle of the night, after everybody else was asleep. It was a way to investigate and craft a self, a soul, undisturbed, unjudged.
The desire for Zen practice must have come from the same rootstock. It's not so much that poetry and zen influenced each other in my life. They were both ways to try to do the same thing, to know the world and my own experience, to feel and think more deeply, with greater saturation. You develop a craft and a practice in order to make a vessel of yourself that can take you where you want you want to go.