silken robe of white

Coleridge reverses the stereotypical link between white/goodness with this initial description of Geraldine. When Christabel first discovers Geraldine behind the Oak Tree, the latter is portrayed as an Angelic, "damsel bright" and her skin is so pale, so "hyper-white", that it makes "that white robe wan". Implicit in the concept of whiteness is the parallel of light; that is, the "damsel bright" and color of white are aligned. However, the exegesis becomes complicated by the entrance of a dark force. The robe "that shadowy in the moonlight shone" brings evil forces, in the form of the shadows, into play. There is a simultaneous tension between the robe trying to "outshine" the shadow, and the powers of evil overcoming the goodness of white/light and taking control. A few stanzas later, white is associated with the horses of the men who "choked (Geraldine's) cries with force and fright" and who abandoned her behind the tree see here This tainting of white by the "five warriors" is pregnant with meaning; white does not strictly adhere to its role of goodness, but can emanate into evil realms. When the "robe" is revisited with this lens, the dominating brightness can be construed as a front for underlying vileness.

So instead of being characterized by purity and goodness, white is associated with malevolent forces in this poem. Indeed, Geraldine's vileness derives from her ignominous spell that imprisons Christabel in her world of sorrow and shame. As an innocent, charitable young lady, Christabel is tricked by Geraldine's whiteness; that is, the color white serves as the innocuous bait that attracts the young lady to the distressed Geraldine and brings about her heartbreak.