I, Juan de Pareja, by Elizabeth Borton de Trevino

This book was just another notch on my "Newbery" belt until about a third of the way through it, when I became intrigued by such a unique story. Juan de Pareja is a black slave who is inherited by reknowned Spanish painter Diego Velazquez. Juan learns to be Diego's helper in the studio, and the two become very loyal and devoted friends. The book spans Juan's lifetime, most of which is spent in service to Diego.

My favorite scene in the book is when Diego gives Juan his freedom, and I was intrigued to learn in the "Afterward" that the whole story is loosely based on the real Diego and Juan. The story in its entirety is very moving, and the book is refreshingly clean and pure...more than any book that I have read in a while.
This book won the Newbery in the 60's, and I can really see why. Trevino speaks out in the "Foreword" about the prevalence yet injustice of slavery worldwide, and a major theme of the book is that slavery -even its most comfortable form (as was between these two friends)- is simply wrong.