9. Light - Dark - Mixed Triplicity of Visible Light

Question:

Darkness can be defined as an "absence of light", and Light can be defined as "the presence of Light". However, Light cannot be defined as "an absence of Darkness", nor can Darkness be defined as "the presence of Darkness".

Why?

Perhaps 20 years ago now, I saw a Hagar the Horrible cartoon that has remained stamped in my memory ever since. I have been searching and searching for a copy of it for a long time, unfortunately haven't yet found it. I had hoped to find a copy so I could put it up here to illustrate the question above, and to serve as a pretext for this discussion on light and dark. Failing this, I will have to explain the cartoon as I remember it.

Hagar is relaxing at home one night, when his friend Eddie comes in late. Eddie says "Boy, its dark outside tonight!" Hagar asks "How dark?". Eddie opens the front door and shows Hagar a thick shaft of darkness streaming through the door into their lit room. Hagar says "Wow! That is dark!"

It bothered me for many years that I could not understand the reason why, like the question above asks, what this cartoon depicted is not possible.