Approximately 1,500,000 Jewish children were murdered during the Holocaust — almost ninety percent of those alive in Europe in 1939. The vast majority of those who survived were hidden, either with their parents, or with strangers. For decades, they were considered too young to remember their experiences during the Second World War. I Didn’t Say Goodbye, by Claudine Vegh, a hidden child who grew up to become a child psychiatrist, was one of the earliest studies of a group known in France a...