I tend to think of it as an unclear, or hidden legend..

4 poetic/literary a ghost.
• ( the Shades) the underworld; Hades.
7.
comparative obscurity.
8.
a specter or ghost.
9.
Greek and Roman Religion . one of the spirits of the dead inhabiting Hades.
10.
a shadow.
18.
to produce shade in or on.
19.
to obscure, dim, or darken.
20.
to screen or hide from view.
21.
to protect (something) from light, heat, etc., by or as by a screen: to shade the eyes from a bright light.