Similarly, the drawing accompanying the important precept Why in twilight shadows on a white surface are blue discussed earlier was completely misinterpreted, posing a serious challenge to the intelligibility of the text. The sky vault was transformed into a proscenium that opens into the landscape but does not participate to the lighting conditions of the landscape, as clearly Leonardo had intended (FIG. 2). These abridged copies transmitted, however badly, Leonardo’s qualitative explanation of shadows but were exceedingly silent on the geometry of light propagation and of reflections, which in Leonardo’s view complemented the qualitative discussion of colors and the atmosphere.