A work of genuine compositional violence — the most angular and geometrically aggressive piece in the entire collection. Where most of Sidney's abstracts use curves, spirals, and organic biomorphic forms, this composition is built around intersecting diagonal lines, sharp geometric planes, and hard-edged forms that crash against each other across the picture surface.
The dominant element is a large red diagonal band that runs from upper left to lower center — a structural beam or road or rupture cutting through the composition at roughly 45 degrees. Against this red diagonal, a counter-diagonal in cooler blue-gray opposes it from the right, creating the central collision from which the title derives. The upper left field is dominated by a tiled yellow ground — warm, flat, domestic — against which a window-like rectangular form with parallel lines reads as architecture or musical notation. At upper center, a large geode-like form in gray-blue provides the only organic element among the geometric forms, connecting this work to the creature and mineral vocabulary of the watercolors.
At lower center, an extraordinary small element: a decorative creature — half flower, half mask — rendered in the meticulous manner of the Portal I geodes, detailed and self-contained amid the geometric chaos surrounding it. This figure is the still point of the composition, the one form that is not moving or colliding but simply being.
The pastel medium here is used with unusual boldness — colors applied in thick layers, surfaces built up and reworked, the board showing through in places as an additional tone. This is Sidney working with maximum physicality.