What happens is that the meaning within the sensory impulses has been grasped. The part of the brain that deals with meaning has received the sensory impulses from the visual cortex and successfully analyzed and integrated the relationship of the visual elements to the whole and to each other. The thing that is more than the sum of the parts, the organized pattern that is there, suddenly bursts into awareness. The meaning is finally perceived and the image that is inside the sensory frame suddenly appears.
