Book excerpt: Joseph Priestley was a pioneering scientist, theologian, and political activist who played a key role in the Enlightenment. This collection of his writings includes his groundbreaking works on chemistry and physics, as well as his provocative religious and political treatises. Priestley's influence on the intellectual and cultural life of his time cannot be overstated, and this volume is an essential resource for anyone seeking to understand the scientific and philosophical debates of the late 18th century. This work has been selected by scholars as being culturally important, and is part of the knowledge base of civilization as we know it. This work is in the "public domain in the United States of America, and possibly other nations. Within the United States, you may freely copy and distribute this work, as no entity (individual or corporate) has a copyright on the body of the work. Scholars believe, and we concur, that this work is important enough to be preserved, reproduced, and made generally available to the public. We appreciate your support of the preservation process, and thank you for being an important part of keeping this knowledge alive and relevant.