Page 5.3.

Locating the view of the table looking straight in at it, is similar to a shadow been cast on the wall by the table when a window is directly in front of the table. Notice here that the shadow cast is the outline of the table top edge, and the legs. The blue lines show the way the light casts the shadow onto the wall. We do not see the shadow cast by the back legs, because the front ones covers them.