OT: Capitalisation to signify uniqueness

Just an odd random observation:

While reading a book on philosophy just now I came
across the word "Reality" spelled with an uppercase
"R" much as we might write "God" with a capital "G".
Yet when we speak of the Roman gods we do not
capitalize the word "gods".  It occured to me that
this is a subtle way that English has of signifying
that the thing under discussion is thought to be the
one and only instance of that thing.  I thought about
a hypothetical world where only one book existed in
the whole world.  If we lived in that world (and
spolke English) surely we would refer to this object
as "The Book", and not simply "the book."

I wondered if other natlangs or conlangs had some
subtle way of signifying that the thing under
discussion was thought to be unique in all of Reality.

--gary