How Do You Start a Piece That You're Going to Write?

Author Roger rosenblatt is an unusual teacher because he brings out the best in you as a writer. He's also wonderful at giving writers prompts. When he starts to write, how do you start a piece that you're going to write? It's almost always an image, not a word,. Then it happened to me when i wrote four seasons all i had was the feet and legs of three couples getting out of ah, that's perfect.