The recent debates on human enhancement ask the question whether enhancing our capabilities is morally desirable. In a sense, the answer is straightforward: to enhance, that is to make things better, is, by definition, a good thing. However, to enhance has a special meaning in the present debates: it consists in going beyond our "natural" capabilities. Is it then still a good thing? To answer this question, it is necessary to ask what is the value of the goods we pursue through enhancement, and this is only possible in the context of a conception of human flourishing. There exist several conceptions of human flourishing; each demands that we improve ourselves in certain directions, depending on the various excellences and on the ideal of the person they promote. But are all means permissible to this effect? Of course not. A set of normative principles is suggested in order to determine which means are permissible. The result of this is that technological and biotechnological means raise no particular problem.