Human enhancement, in which nanotechnology is expected to play a major role, continues to be a highly contentious ethical debate, with experts on both sides calling it the single most important issue facing science and society in this brave, new century. This paper is a broad introduction to the symposium herein that explores a range of perspectives related to that debate. We will discuss what human enhancement is and its apparent contrast to therapy; and we will begin to tease apart (...) the myriad intertwined issues that arise in the debate: (1) freedom & autonomy, (2) health & safety, (3) fairness & equity, (4) societal disruption, and (5) human dignity. (shrink)