The "object lesson", a traditional teaching method that has been somewhat forgotten, consists of presenting an everyday object by naming its characteristics and properties. For this lesson, the object in question and the place are not indifferent. Herman Asselberghs, whose attachment to uncovering from film to film the ideological springs at work in technological objects is well known, chooses a camera, more precisely a Black Magic. The lesson is conducted in a school by film students. Two forms of devices, therefore, and of course the object is the very tool of the film unfolding before our eyes. From this starting point, Asselberghs leads step by step to the heart of the act of seeing, of filming. Playing with sound with malice, he thwarts the false evidence of the visible and its pitfalls. Paradoxes and twists of meaning are highlighted by the decision to film the students of the school in fixed shots, while each one is absorbed in a task: listening, watching, reading, in an architecture with displayed transparency, supported by a surveillance camera. The camera and the place of learning: two machines for manufacturing the modalities of the gaze that we have on reality? Two vision machines? At the very least, the film invites us to a movement of thought between opacity and visibility, from the dark room dedicated to appearances to this ideologically transparent box that is architecture here. A dizzying object lesson, where a reflection on the manufacture and processing of images, the control they produce, and absorption as a vanishing point are played out.