X used to love to play in sunbeams. When he was not yet mobile, I would sit him down in a sunbeam and he would smack it with his hands and try to pick it up, and sometimes try to taste it on the floor (yucky!). When he started to crawl, he would go into the front hallway and sit in the sunbeams from the setting sun, and follow them as they climbed the wall. Random bits of sunlight were a delight to pluck at on my shirt, or my arm.
It seems he barely noticed the play of the light on his bedroom floor this morning. He didn't shriek with delight, or try to grab up the glow. He is the sunbeam, now.