Heinz Mack, founding member of the artist group "ZERO" and master of reduction, earned his spot in post-war art with a body of works characterized by the phenomen of light incidence and changing optical impressions. Owing to the artistic integration of light and shade, Mack's creations leave their material grounds and become works of ever changing ephemeral sensory impressions. As far as the choice of subject is concerned, Mack's poetic works elude any form of concreteness, additionally, they allow the observer to participate in a metaphysical art experience, which is also emphasized through its spatial presence and three-dimensionality. Due to the grid motion's subtlety and lightness, Mack realized a work with a particular optical intensity and expressiveness.