Scientists and other keen observers of the natural world sometimes make or write a statement pertaining to scientific activity that is destined to live on beyond the brief period of time for which it was intended. This book serves as a collection of these statements from great philosophers and thought--influencers of science, past and present. It allows the reader quickly to find relevant quotations or citations. Organized thematically and indexed alphabetically by author, this work makes readily available an unprecedented collection of approximately 18,000 quotations related to a broad range of scientific topics.