The classical view of babies' minds was that they didn't really think much and they weren't very interesting. But that's not the experience of any parent. This book suggests that in fact, babyhood is the most interesting and challenging time, when intrinsic understanding and implicit beliefs about the world are formed that shape the adult to come. It's not easy to prove these beliefs and understanding in pre-verbal children, but this book summarises the fascinating and revealing work that has been done to elucidate them. Play is the work of the child; through play they can experiment with objects and with roles and develop their own philosophy of life.