This classic work of popular science explores the possibility of extraterrestrial life and the implications of such a discovery for religion, philosophy, and ethics. The author covers a range of topics, from astronomy and physics, to biology and theology, to argue that there is strong evidence to support the existence of other worlds and the likelihood of life on other planets. He also considers the ethical and spiritual implications of such a discovery, and suggests that it could ultimately bring humanity closer together in a shared sense of awe and wonder. 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.