A background in mathematics gives my enchantment with words a special twist. Each time I see familiar math terms in a poem I layer their mathematical meanings amid their mainstream ones. Two such terms are "open" and "closed." (I'll supply brief mathematical explanation at the end of this post but, first, here is "Open and Closed Spaces" -- a poem by the winner of the 2011 Nobel prize for Literature, Swedish poet Tomas Transtromer. )
Open and Closed Spaces by Tomas Transtromer
A man feels the world with his work like a glove.
He rests for a while at midday having laid aside the gloves on the shelf.
There they suddenly grow, spread
and black-out the whole house from inside.
The blacked-out house is away out among the winds of spring.
'Amnesty,' runs the whisper in the grass: 'amnesty.'
A boy sprints with an invisible line slanting up in the sky
where his wild dream of the future flies lika a kite bigger than the suburb.
Further north you can see from a summit the blue endless carpet of pine forest
where the cloud shadows
are standing still.
No, are flying.
This poem is in Transtromer's collection, New Collected Poems, translated by Robin Fulton (Bloodaxe Books, 1997/2011). The Swedish original of "Open and Closed Spaces" and several other Transtromer poems (selected by Lars Rydquist, head librarian, Nobel Library of the Swedish Academy) are available at the Nobel prize web site.
In mathematics an intuitive characterization of an "open" set of points is that each of its points is surrounded by points also in the set. For example, the points interior to a circle form an open set. The circle itself is a set of boundary points for the interior points. If we add these boundary points to the interior points we have a "closed" set.