Editor: Here we have an X-radiograph of "Philippe de Croy" by Rogier van der Weyden. It's so interesting to see beneath the surface. What can you tell me about its composition? Curator: Observe how the densities vary, creating a hierarchy of forms. The lighter areas indicate denser materials. Notice the stark contrast between the subject and the background, achieved through varying pigment application. Editor: So, the artist strategically used materials to achieve this visual effect? Curator: Precisely. The formal relationships here speak to the artist's mastery of layering and manipulation of materials. The interplay of textures and forms is a compelling formal study. Editor: I'm beginning to see how the X-ray reveals intentional structural choices. Curator: Indeed, it is a fascinating glimpse into the artist's process and material decisions.