One of the fruits of the scientific revolution was the idea of a social science - a science of government, of individual behaviour, and of society - that would operate in ways comparable to the newly triumphant natural sciences. Thus was set in motion a long and often convoluted chain of two-way interactions that still have implications for both scholarship and public policy. This text, by the dean of American historians of science, offers a historical perspective on these interactions. The core of the book consists of two essays. The first focuses on the role of analogies as linking factors between the two realms. Examples are drawn from the physics of rational mechanics and energy physics (in relation to marginalist or neo-classical economics) and from the biology of the cell theory (in relation to 19th-century sociology). The second essay looks closely at the relations between the natural and the social sciences in the period of the Scientific Revolution. The book also includes a record of a series of conversations between the author and Harvey Brooks (Professor of Technology and Public Policy Emeritus at Harvard) that addresses the present-day public policy implications of the historical interactions between the natural and the social sciences. A short history of the terms "natural science" and "social science" concludes the book.