This paper describes the origins of nanoscience from theoretical reasoning to its realization in terms of mechanical manipulation of atoms. The ability to visualize and manipulate matter at the nanoscale has led to a diverse technology that ranges from better and faster electronics and more efficient fuel usage to sensing, drug discovery and stronger, more resistant materials. It has the prospect of affecting the lives of all of us and already a number of applications are in the market-place. But in our development of these technologies, we need to take care to reduce the risks of the adverse consequences that usually attend new applications of science.