Alvin Maker by Orson Scott Card
This book begins as one book, almost an adventure story in the classical science fiction vein and segues into one of the most compelling, metaphysically profound stories of the unfolding of human history and culture ever written. How a small accident under the right circumstances changed the life of a man and the entire world that he lived in for generations to come.
The circumstances Jason Worthing found himself in will stay in your memory long after you have finished this book. Absolutely one of Card's best.