Because it's a quotation from someone who experienced what Russel Freedman exposes in his book. Then, Edward Corsi can, not only give a personal view about the facts, but also offers another information and experience to the book.
Explanation:
Russel Freedman's book is a set of texts and photographs that can tell us a story. His book gives us a glimpse of the early days of immigration in the 1900s, but through the lens of a photographer. In many ways, Edward Corsi's quotation for this book offers a personal view of the situation of immigrant children. If Corsi was one of them, he can say more about the situation than a photograph. He can go deeper and exposes more than a photo can do.
