It's an ethical pact I've made with myself and with the reader - not to invent. And when I can't remember, I say I can't remember. I'm just appalled by the memoirs published by people who regurgitate dialogue, conversations from when they were small children, and they go on for three or four pages. I can't even remember what we said to each other ten minutes ago! How can I remember what was said sixty years ago? It's not possible.