Piero di Cosimo- Prometheus

The statue’s head stands at the vertex of the converging 45-degree diagonals rising from the panel’s bottom corners. The body of Jupiter and the building behind him are fixed between the left diagonal and the arc rising to the statue’s head; on the right half of the panel, the arc may similarly have located the tree in the background, the placement of Prometheus’s head, Minerva’s hand, and the plant cluster at the bottom margin. The shallow red diagonals have an inclination of 18 degrees, the angle that one finds in decagons, a figure that Piero used in other paintings. The one rising from the lower left corner traces Epimetheus’s knees, the clay man’s ankle, the tip of the table leg to the left of the statue, and the angle of Prometheus’s arms, before passing along Minverva’s chin. The line descending from the left margin passes by the base of the tree at left, paralleling Jupiter’s shoulders, Prometheus’s knee, and Minerva’s foot.

When 45-degree lines are launched from the intersections of the red lines with the left and right panel margins, points are located along the top margin of the panel from which other longer orange lines are launched to the bottom corners of the panel. These long lines cross just above the statue’s genitals. The orange line rising from the lower left corner passes along the leg of the clay man, through its genitals, and along the border between Jupiter’s red robe and blue mantle. The short diagonal at upper right passes along the garland of fabric trailing from the airborne Prometheus and Minerva. The long orange line descending from the statue passes through Prometheus’s elbow and along the border between the red and blue parts of Minerva’s costume.

Here yellow lines of 30-degree slope have been added through the lower corners of the panel. These lines converge at the level of the statue’s knees, aligning also with the heads of Jupiter, Prometheus, and Minerva. The yellow line rising from the lower left corner passes through the clay figure’s knee, along the bottom of a cloud bank, and along the backs and through the faces of the flying Minerva and Prometheus.

Here a green horizontal has been drawn through the points where the sloping red lines meet the left and right margins of the panels. This horizontal aligns with the tops of the buildings behind Jupiter, and with the top of Prometheus’s raised hand. The structure immediately behind Jupiter stands just above the point where the red diagonal intersects the yellow horizontal. Green diagonals launched from the center of the panel’s bottom margin pass along the edges of the statue base, and through the torsos of Jupiter and Prometheus, before intersecting the yellow horizontal at points aligned with a house at left and with Prometheus’s elbow at right. The vertical rising from that elbow also passes by the feet of the flying pair. Finally, the steep green lines departing from the lower corners of the panel are inclined at 72 degrees, the complement of the 18-degree red lines introduced earlier. The left of these green lines passes through the hand of the kneeling Epithemeus, and along the back of the small climbing figure behind him, which is his future self. The corresponding line at right passes along the leg of the flying Minerva, and along the adjacent garland. The overall composition thus involves lines based on the slopes of the equilateral triangle (30 degrees), the square (45 degrees), and the pentagon/decagon (18 degrees and 72 degrees).

A series of decagons and half-decagons also help to govern the composition. When a half-decagon is placed with its center on the left margin of the panel and aligned with the yellow horizontal, one sees that its most steeply descending ray parallels the body of Epimetheus, and that its next three rays meet the knee, elbow, and shoulder of the clay man. Its rightmost facet below the painting’s equator aligns with the torso of Jupiter. The equivalent facet of a half-decagon centered on the right margin of the panel aligns with the torso and left leg of the standing Prometheus, while the airborne Prometheus and Minerva fit into this decagon’s upper diagonal sector. A slightly smaller full decagon centered on the yellow horizontal and with its top facet aligned with the top edge of the painting has right facets aligned with the forearm and torso of the standing Prometheus, while the endpoints of its bottom facet locate objects such as the lump of clay in the left foreground, while corners of its upper diagonal facets locate the figures in the clouds. Most importantly, though, its center coincides with the left knee of the standing statue, and the V-shaped line from that center to the endpoints of its top facet embraces the statue’s torso, while aligning with its left leg and left forearm. A similar but even smaller decagon centered just above the statue’s genitals, where the orange diagonals cross, produces an analogous V-shape whose faces pass along the left side of the statue’s torso, and intersect the statue’s pointing right hand. The lower left corner of this decagon coincides with Jupiter’s left shoulder. All of these relationships serve to underscore the importance of the decagonal symmetries already introduced by the red 18-degree lines in the first step of this analysis.

This painting is the property of the Alte Pinakothek, in Munich, Germany. This analysis was based on the image: https://commons.wikimedia.org/wiki/File:Piero_di_cosimo,_prometeo.jpg