What is the theme in A Moveable Feast by Ernest Hemingway?

Friendship is a major theme. Hemingway considers many of the people he describes in his book as "friends," and he implies much about what friendship means to him, how it is won, and how it is lost. Among those Hemingway seems to count his friends are Ezra Pound, Evan Shipman and F. Scott Fitzgerald. He considers Gertrude Stein a friend, but depicts an episode where he loses the ability to continue thinking of her as a friend.