This issue 4 of ARTis ON journal aims to examine the questions raised by the contemporary practice of installation in relation to the notion of medium and to explore the implicit considerations for the concepts of art history. This issue also counts on two essays unpublished in Portuguese, particularly relevant to a reflection on the medium and intermediality today. The first is from Jacques Rancière and never was published in a book. The second is a text published by Juliane Rebentisch in “The Plural of Art”, constituting a translated chapter from her recent book Theorien der Gegenwartskunst.