This work by Manfredo Massironi is a square divided into its four quadrants. Centrally in each quadrant, for example the one on the left at the top, Massironi places an aluminum square which he rotates clockwise and at the same time enlarges its dimensions. For successive rotations and enlargements at the end, the square occupies the entire quadrant obtaining four circular sectors with tangential elements that end up orthogonally against the contiguous sector. Massironi then flips this figure around the vertical axis and then flips both figures around the horizontal axis covering the entire surface concerned. Visually, the eye perceives four open fans and eight half-open fans. From here we appreciate the value of the artist in the study of visual perception of which he was a great scholar and supporter.