What word does he prepositional phrase in the middle modify?

“heartwork each day is born with a sunrise and ends in a sunset, the same way we open our eyes to see the light, and close them to hear the dark. you have no control over how your story begins or ends. but by now, you should know that all things have an ending. every spark returns to darkness. every sound returns to silence. and every flower returns to sleep with the earth. the journey of the sun and moon is predictable. but yours, is your ultimate art.” ― suzy kassem what does this quote mean to you? and why? i'm not looking for anything in particular, i just wanted to know. : )