A good instance of the very simple explanations and theoretical solutions that, "hiding in plain sight", manage to possibly remain unseen for a very long time.

I nearby noted that "you do not cast your shadow on your documents" and that "you gather around a fire facing it". There is something even simpler:

___ the sun is above. ___

So, to represent something with a light coming from "the south" is as unnatural as lighting a face from below.