More specifically, Gould showed that the chapel geometry could be found by creating isosceles triangles, here shown in green, whose short bases correspond to the radii of the normal chapels, and whose long sides parallel the side of the squares framing the third and fifth chapel. Because of the subdivision of the chevet into 27-degree slices, the sharp angles in these triangles measure 36 degrees. Each green triangle thus resembles the tip of a pentagonal star, a figure whose proportions are defined by the Golden Section. I’d be remiss not to mention that well-known relationship, but I won’t explicate it further, since I have more specific arguments to makes about Saint-Denis. I should point out, for example, that the center of the axial chapel can be found by striking lines from the adjacent chapel centers at a pentagon-defined angle of 72 degrees, as the green lines near the top of the figure indicate. Everything I have said in the past few minutes comes from Gould’s analysis, which impressed me greatly. In the rest of my talk, I want to build on his foundation. To begin with, I want to locate certain important elements in the crypt that he did not discuss, starting with the red shaded arc that separates the ambulatory from the chapels.