How much math does a math-poem need?

Poems offered in this blog vary in the levels of mathematics they contain.  One mathematical reader commented privately that in some of the poems the use of mathematical terms is "purely decorative."  Indeed, some people have particular expectations for poetry that relates to mathematics -- they want the content to use mathematical notation or to present a mathematical truth. Such as, perhaps, this abbreviated statement of the four-color theorem (formulated as a 4x4 square): 

          Any flat map
          we draw we may
          color with four
          colors only.

My view is that appreciation of mathematics in a poem may be experienced from one or two well-chosen images -- as well as from a more mathematically-dense display.  In this post I feature work by John Vieira, an artist and poet who uses a small amount of mathematics very well.  (To explore further the poetry of pure mathematics, visit postings for 11 November 2010  or 14 July 2010 or 29 April 2010.)

    The Lake Swan, the Tom     by John Vieira

     The lake swan, the tom,

     Swimming love’s vector

     Diagonally across, connects

     For her, unassumingly

     With his neck’s curve,

     The mountain and the deep,

     Wet black underneath.

     How when she comes upon

     The same scene later

     And, unable to locate

     Her eye’s companion,

     Cries uncompromisingly

     For his clear, white

     Figure again to appear.

"The Lake Swan. the Tom" first appeared in Agni (22, then 56) and also is found in the anthology Strange Attractors:  Poems of Love and Mathematics ( A K Peters, 2008).  Here, next, is an example of Vieira's visual art:

Tallies  by John Vieira