“The very notion of human enhancement is usually defined in contrast to therapy or intervention against the disorders: while therapy aims to cure disorder and bring bodily and/or mental functionality up to (or towards) normal levels, enhancement aims to lift functionality beyond such levels. But “normal” is a fuzzy concept, and some of the above examples indicate the difficulty of drawing a clear line in the sand. Some writers argue that we can and must do so, whereas others are more skeptical about the distinction, such as Wolpe (2002), who characterizes it relativistically as “what medicine chooses to treat is defined as disease, while altering what it does not treat is enhancement.””

— Olle Häggström, Here Be Dragons: Science, Technology and the Future of Humanity, Chapter “Engineering better humans?”, p. 38