Abstract
The aim of this lecture is to show the usefulness of the concept of the "invisible library", to make visible and concrete what, in these invisible libraries, would tend to escape our gaze, all the more so as between the invisible library and us stands another library, quite material, likely to monopolize all our attention: the library as a real institution, as a place situated in space and time. The visible library is the mask of the invisible library.
What is referred to here as the "invisible library" or "mental library" refers to a set of works of a linguistic nature of which an individual or group may have a more or less distinct awareness or representation. In other words, it is a mental representation of collections of works and texts, existing at the individual or collective level, more or less explicit or conscious, and which, although mental and non-material, nonetheless sometimes exerts effects on reality. This last point is important: if invisible libraries were to remain invisible forever, we might well lose interest in them and regard them as negligible objects. But it's precisely because these libraries have an impact on the world that we should be interested in them. One of the main effects of mental libraries is the creation and organization of real libraries. Every material library reflects an invisible library, that of its creators. There is no empirical library that is not preceded by a mental representation of the organization of its constituent works. Another difference between the material library and the invisible library is that an invisible library does not need a material library to exist; but the reverse is not true. Every material library is based on an invisible library.
