When we are newborns, we gradually learn to distinguish the blur of colors and shapes around us, to recognize them as individual objects, as parents, as the doggy, as the blanket, as big sister, as the spoon. We learn to pay attention to the objects and individuals, and to somewhat ignore the shadows they cast as something intangible. We learn the require less focused attention than the light reflected off the surrounding creatures and furniture and objects.
In my 60s, as I write in this blog I named 'the dark & the light', I've come to take more notice of shade. Perhaps we underestimate shadow.