How does Eudora Welty use imagery in The Optimist's Daughter?

In our reading of Welty's novel, we come to understand her purpose in part through the special cogency of her dominant imagery, that of vision and blindness. On the surface it appears that Welty is simply exploiting the traditional meanings of these images, using them as expressions of the broader symbolism of light and darknessas emblems of human understanding. But as is true of her use of imagery throughout the novel, she evokes the full range of meanings implicit in each symbol, from the most positive to the most negative. Light connotes illumination, comprehension, and clarity, yet its excess leads to just the opposite. Similarly, the darkness that normally signifies obscurity, ignorance, or an inability or unwillingness to understand can also imply a restfulness that makes introspection and later "vision" possible.