The film Line Describing a Cone was made in 1973 and it was projected for the first time at Fylkingen (Stockholm) on 30 August of the same year. This piece, which was initially screened in independent film contexts, it soon began to be shown at art museums and ended up becoming one of the key works of the artistic movement that opened up the visual arts towards cinema. With a duration of 30 minutes, the film shows the creation of a white curve being projected onto an empty space. A thin mist is introduced into the projection area, therefore the viewer can progressively see (more than a circle reflected on the wall) a large cone of light which simultaneously becomes a light sculpture into which he is invited to circulate. By allowing the viewer to immerse himself in it, and play with this strange substance, Line Describing a Cone becomes not only something made to be seen, but also something to be experienced since the viewer is absorbed into the scene and becomes part of the action. In this way, McCall recreates an inversion: by placing the public facing the projector, he reveals the entire process of kinematics and, at the same time, he destroys any possibility of illusionism, in order to create another, that of magic, poetry and wonder.