What is the source? Where does it come from? How do you do it?
The answer to those questions depends on the artist and their art. If your art is the practice of bodhicitta- the wish to bring about the benefit of others through generosity, love and kindness, then your muse is reality. It is the interactions that take place, the conversations that unfold, the stories that are shaped like the convergence of the wind and leaves.
It is random and unpredictable, but if your mind is open and receptive you will be surprised at what you can hear.
You'll discover an unending stream that continuously unfolds, presenting you with opportunities to give gifts that matter, to practice your art.