The so-called "virtual world" is often described with the help of metaphors derived from ordinary discourse on perception and action. This should not be surprising, since virtual objects were partly conceived on the basis of these metaphors. Yet, it is not a given that these metaphors are appropriate; one might need to begin using different concepts and eventually to invent new ones, more appropriate to the phenomena they describe. It might even happen, as I shall show, that these new concepts will themselves be used in situations described by the discourses on perception, action and social behaviour in a way that so far seems perfectly natural, but that, in turn, might reveal itself to be entirely inadequate. One could use these new metaph...