First published in 1870, this collection of essays explores the relationship between scientific reasoning and imagination. The author argues that creativity and intuition are integral to scientific discovery, but that they must be tempered by rigorous empirical study. This book will appeal to readers interested in the history and philosophy of science. 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.