Lincoln and Euclid -- common notions

     This afternoon I enjoyed the recently-released film, Lincoln -- appreciating Sally Fields as Mary Todd, Tommy Lee Jones as Thaddeus Stevens and (especially) Daniel Day-Lewis as Abraham Lincoln. An absorbing drama -- inspiring and also informative.  With a slight mention of mathematics:  in a film conversation with two-young telegraph operators, Lincoln reflected on his study of Euclid and shared with the young men the first of Euclid's common notions:

     Things that are equal to the same thing are equal to each other. 

     In Lincoln's musings, Euclid's notion of equal resonated with considerations of the 13th amendment and the abolition of slavery.  Throughout the film, President Lincoln showed a politician's way, as poets also have, of stretching words to their multiple meanings.
     Massachusetts poet Anne Porter (1911-2011) published her first poetry book at age 83.  Porter, like Lincoln, stretches the meaning of equal -- here, below, in her poem "Winter Twilight."

          Winter Twilight       by Anne Porter 
 
          On a clear winter's evening
          The crescent moon

          And the round squirrels' nest
          In the bare oak

          Are equal planets.

From Living Things by Anne Porter, found at poets.org (Zoland Books, 2006).