The concept of self-description plays an important role in Niklas Luhmann's sociological systems theory. In the systems theoretical sense, self-description does not mean description of self but description of society by society itself. The implication of self-description (of society) lies in that we cannot describe society from outside of society. From the systems theoretical viewpoint, we can see society as a system that contains various self-descriptions and therefore we should not ask what society is but how society is described. Systems theoretical description is the meta-level description (i.e. second-order observation). It can especially be characterized as the description of differences. Meta-level observers try to indicate what kind of distinctions or borderlines are drawn in a certain observation or description. Such a viewpoint enables us to see the hidden side (blind spot) of description of society and that is indeed the advantage and the true charm of the systems theoretical description.