“Humans constantly, but unconsciously, use shadows to judge the shape and location of objects in their environment.” Humans are simply not used to seeing the shadows formed by a light source located beneath. this investigation began with 

Shadows in renaissance art which were used to define perspective however do not feature frequently, one reason for this maybe that they were considered ugly, Leonardo said, “that the representation of shadow had to be correct but not obligatory.”

Masaccio’s, St. Peter healing the sick with his shadow, used the ancient representation of the healing shadow with newly acquired capacity of painting an extremely refined process; he brings together to origins (sacred and scientific) in this mise en scene of the shadows power.

Historically the Greeks saw, the shadow as one of the metaphors for the psyche, the soul. A dead person’s soul was compared to a shadow, and Hades was the land of shadows.

In Plato’s story about the origin of knowledge, which contributed to this negative validation, you must renounce the world of shadows before you can accede to true understanding.