“Our lives don’t happen chronologically in memory, and a good memoirist has to know how to structure that memoir in a way that you can see the shaping of a life....” Amy Tan, whose second memoir, Where the Past Begins: A Writer’s Memoir (Ecco, 2017), is featured in Page One of the November/December issue of Poets & Writers Magazine, talks about the genre and about Mary Karr’s memoir writing.