Transformation in Literature

What is a transformational book? To me, a transformational book changes the way you look at things. One of the most transformational book I've ever read is Challenger Deep. It helped me imagine the experience of someone with a mental illness. The main character, Cayden, seemed like a teenage boy not to different than most. As the book went on I experienced his descent into schizophrenia right alongside him. This book completely changed my perspective on what it's like to live with mental illness and have everyone call you "crazy" and a "burden to your family" for something that you can't control. This book is transformational and I think anyone who may be discriminatory towards the mentally ill should read it.