On Internal Tension and the Word "About"

"About" means "concerned with" as in "this article is about the war in Iraq." Used in this way it refers to the central point of something, its gist, its core. Whatever meaning beats at its heart.

But "about" also means "near," "close to," "approximately," as in "it was about 6:30 am when the sun rose on one side of the Bay Bridge."

And it means "all around" as in "there were flowers planted all about the castle."

On in near around at the center of. Is there any preposition that "about" does not contain?

Sometimes I feel sad and my sadness is not "about" anything. This might sound strange unless you think of moods being like the weather -- the sun does not rise "about" anything -- it just rises. Or unless you think about the other meanings of "about" -- the sun rises and casts its light all about the city.