Photography, in particular black and white photography, has sometimes been described as sculpting with light. This is why black and white art based photography so often focuses on texture and shape which, in my experience, tends to stand out more strongly when set against either a very dark or a white background. Just as the dark parts of the image appear as if through the eerie light of the chemicals in the tray, like inverted ghosts ,so what remains white or light, shapes what the eye sees, and the movement of an image becoming more defined guides the eye through the composition. It is often at this stage that one can really see whether the composition is balanced, whether the focal point is where the eye is naturally drawn or whether there are distractions that muddy the waters.
Bathed in red light, the darkness becomes increasingly visible and, hopefully, the image implants itself on the retina and remains there even after the session in the darkroom has been concluded.