|Penumbra ( an explanation of the analogy )
..... "The Shadows" are the shadow – sound-a-likes and imitators are quasi shadows .....
Thus in terms of this analogy ..... "The Shadows" are the "umbra" – and we all comprise the "penumbra"
|The latin word for a shadow is "umbra", and as in the image above, this is the central (darkest) portion of the shadow being cast by the sphere, which in turn is being illuminated by a single light source. Within the "umbra" itself, the source of light is totally blocked by the sphere casting the shadow, contrasting with the "penumbra", or area extending beyond the spherical shadow where the light source is only partially blocked - an area of partial, ever-diminishing shadowing. The first three letters of the word "penumbra" derive from the Greek word "paene" for almost.
The "penumbra" phenomenon is more easily demonstrated/understood by the use of dual light sources as below. Here two shadows are cast, and the "umbra" is easily distinguished between two areas of partial shadowing or "penumbra".